Dataset class for MySQL datasets accessed via the native driver.
Dataset class for PostgreSQL datasets that use the pg, postgres, or postgres-pr driver.
A dataset represents an SQL query, or more generally, an abstract set of rows in the database. Datasets can be used to create, retrieve, update and delete records.
Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):
my_posts = DB[:posts].filter(:author => 'david') # no records are retrieved my_posts.all # records are retrieved my_posts.all # records are retrieved again
Most dataset methods return modified copies of the dataset (functional style), so you can reuse different datasets to access data:
posts = DB[:posts] davids_posts = posts.filter(:author => 'david') old_posts = posts.filter('stamp < ?', Date.today - 7) davids_old_posts = davids_posts.filter('stamp < ?', Date.today - 7)
Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.
For more information, see the "Dataset Basics" guide.
Action methods defined by Sequel that execute code on the database.
The dataset options that require the removal of cached columns if changed.
Which options don’t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.
These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.
These symbols have _join methods created (e.g. natural_join) that call join_table with the symbol. They only accept a single table argument which is passed to join_table, and they raise an error if called with a block.
All methods that return modified datasets with a joined table added.
Methods that return modified datasets
All methods that should have a ! method added that modifies the receiver.
The database related to this dataset. This is the Database instance that will execute all of this dataset’s queries.
Set the method to call on identifiers going into the database for this dataset
Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.
# File lib/sequel/dataset/sql.rb, line 181 181: def self.clause_methods(type, clauses) 182: clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze 183: end
# File lib/sequel/dataset/sql.rb, line 326 326: def self.def_append_methods(meths) 327: meths.each do |meth| 328: class_eval( def #{meth}(*args, &block) s = '' #{meth}_append(s, *args, &block) s end, __FILE__, __LINE__ + 1) 329: end 330: end
Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.
# File lib/sequel/dataset/mutation.rb, line 14 14: def self.def_mutation_method(*meths) 15: meths.each do |meth| 16: class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__) 17: end 18: end
Enable column introspection for every dataset.
# File lib/sequel/extensions/columns_introspection.rb, line 56 56: def self.introspect_all_columns 57: include ColumnsIntrospection 58: remove_method(:columns) if instance_methods(false).map{|x| x.to_s}.include?('columns') 59: end
Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:
DB[:posts]
Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.
# File lib/sequel/dataset/misc.rb, line 28 28: def initialize(db, opts = nil) 29: @db = db 30: @opts = opts || {} 31: end
Inserts the given argument into the database. Returns self so it can be used safely when chaining:
DB[:items] << {:id=>0, :name=>'Zero'} << DB[:old_items].select(:id, name)
# File lib/sequel/dataset/actions.rb, line 22 22: def <<(arg) 23: insert(arg) 24: self 25: end
Define a hash value such that datasets with the same DB, opts, and SQL will be consider equal.
# File lib/sequel/dataset/misc.rb, line 35 35: def ==(o) 36: o.is_a?(self.class) && db == o.db && opts == o.opts && sql == o.sql 37: end
Returns the first record matching the conditions. Examples:
DB[:table][:id=>1] # SELECT * FROM table WHERE (id = 1) LIMIT 1 # => {:id=1}
# File lib/sequel/dataset/actions.rb, line 31 31: def [](*conditions) 32: raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0 33: first(*conditions) 34: end
Update all records matching the conditions with the values specified. Returns the number of rows affected.
DB[:table][:id=>1] = {:id=>2} # UPDATE table SET id = 2 WHERE id = 1 # => 1 # number of rows affected
# File lib/sequel/dataset/actions.rb, line 41 41: def []=(conditions, values) 42: filter(conditions).update(values) 43: end
Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_more when graphing). See set_graph_aliases.
DB[:table].add_graph_aliases(:some_alias=>[:table, :column]) # SELECT ..., table.column AS some_alias # => {:table=>{:column=>some_alias_value, ...}, ...}
# File lib/sequel/dataset/graph.rb, line 17 17: def add_graph_aliases(graph_aliases) 18: columns, graph_aliases = graph_alias_columns(graph_aliases) 19: ds = select_more(*columns) 20: ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || (ds.opts[:graph][:column_aliases] rescue {}) || {}).merge(graph_aliases) 21: ds 22: end
SQL fragment for AliasedExpression
# File lib/sequel/dataset/sql.rb, line 341 341: def aliased_expression_sql_append(sql, ae) 342: literal_append(sql, ae.expression) 343: as_sql_append(sql, ae.aliaz) 344: end
Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.
DB[:table].all # SELECT * FROM table # => [{:id=>1, ...}, {:id=>2, ...}, ...] # Iterate over all rows in the table DB[:table].all{|row| p row}
# File lib/sequel/dataset/actions.rb, line 53 53: def all(&block) 54: a = [] 55: each{|r| a << r} 56: post_load(a) 57: a.each(&block) if block 58: a 59: end
Adds an further filter to an existing filter using AND. If no filter exists an error is raised. This method is identical to # except it expects an existing filter.
DB[:table].filter(:a).and(:b) # SELECT * FROM table WHERE a AND b
# File lib/sequel/dataset/query.rb, line 45 45: def and(*cond, &block) 46: raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where] 47: filter(*cond, &block) 48: end
Returns the average value for the given column.
DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1 # => 3
# File lib/sequel/dataset/actions.rb, line 65 65: def avg(column) 66: aggregate_dataset.get{avg(column)} 67: end
Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.
DB[:table].filter(:id=>:$id).bind(:id=>1).call(:first) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 217 217: def bind(bind_vars={}) 218: clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars) 219: end
SQL fragment for BooleanConstants
# File lib/sequel/dataset/sql.rb, line 358 358: def boolean_constant_sql_append(sql, constant) 359: if (constant == true || constant == false) && !supports_where_true? 360: sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE) 361: else 362: literal_append(sql, constant) 363: end 364: end
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.
DB[:table].filter(:id=>:$id).call(:first, :id=>1) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 228 228: def call(type, bind_variables={}, *values, &block) 229: prepare(type, nil, *values).call(bind_variables, &block) 230: end
Execute the given type of statement with the hash of values.
# File lib/sequel/adapters/postgres.rb, line 673 673: def call(type, bind_vars={}, *values, &block) 674: ps = to_prepared_statement(type, values) 675: ps.extend(BindArgumentMethods) 676: ps.call(bind_vars, &block) 677: end
Execute the given type of statement with the hash of values.
# File lib/sequel/adapters/oracle.rb, line 367 367: def call(type, bind_vars={}, *values, &block) 368: ps = to_prepared_statement(type, values) 369: ps.extend(BindArgumentMethods) 370: ps.call(bind_vars, &block) 371: end
SQL fragment for CaseExpression
# File lib/sequel/dataset/sql.rb, line 367 367: def case_expression_sql_append(sql, ce) 368: sql << CASE_OPEN 369: if ce.expression? 370: sql << SPACE 371: literal_append(sql, ce.expression) 372: end 373: w = CASE_WHEN 374: t = CASE_THEN 375: ce.conditions.each do |c,r| 376: sql << w 377: literal_append(sql, c) 378: sql << t 379: literal_append(sql, r) 380: end 381: sql << CASE_ELSE 382: literal_append(sql, ce.default) 383: sql << CASE_END 384: end
Returns a new clone of the dataset with with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.
# File lib/sequel/dataset/query.rb, line 54 54: def clone(opts = {}) 55: c = super() 56: c.opts = @opts.merge(opts) 57: c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)} 58: c 59: end
SQL fragment for specifying all columns in a given table
# File lib/sequel/dataset/sql.rb, line 395 395: def column_all_sql_append(sql, ca) 396: qualified_identifier_sql_append(sql, ca.table, WILDCARD) 397: end
Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.
If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.
DB[:table].columns # => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 78 78: def columns 79: return @columns if @columns 80: ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1, :offset=>nil) 81: ds.each{break} 82: @columns = ds.instance_variable_get(:@columns) 83: @columns || [] 84: end
Ignore any cached column information and perform a query to retrieve a row in order to get the columns.
DB[:table].columns! # => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 91 91: def columns! 92: @columns = nil 93: columns 94: end
SQL fragment for the complex expression.
# File lib/sequel/dataset/sql.rb, line 400 400: def complex_expression_sql_append(sql, op, args) 401: case op 402: when *IS_OPERATORS 403: r = args.at(1) 404: if r.nil? || supports_is_true? 405: raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r] 406: sql << PAREN_OPEN 407: literal_append(sql, args.at(0)) 408: sql << SPACE << op.to_s << SPACE 409: sql << v << PAREN_CLOSE 410: elsif op == :IS 411: complex_expression_sql_append(sql, :"=", args) 412: else 413: complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)]) 414: end 415: when :IN, :"NOT IN" 416: cols = args.at(0) 417: vals = args.at(1) 418: col_array = true if cols.is_a?(Array) 419: if vals.is_a?(Array) 420: val_array = true 421: empty_val_array = vals == [] 422: end 423: if empty_val_array 424: literal_append(sql, empty_array_value(op, cols)) 425: elsif col_array 426: if !supports_multiple_column_in? 427: if val_array 428: expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})}) 429: literal_append(sql, op == :IN ? expr : ~expr) 430: else 431: old_vals = vals 432: vals = vals.naked if vals.is_a?(Sequel::Dataset) 433: vals = vals.to_a 434: val_cols = old_vals.columns 435: complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}]) 436: end 437: else 438: # If the columns and values are both arrays, use array_sql instead of 439: # literal so that if values is an array of two element arrays, it 440: # will be treated as a value list instead of a condition specifier. 441: sql << PAREN_OPEN 442: literal_append(sql, cols) 443: sql << SPACE << op.to_s << SPACE 444: if val_array 445: array_sql_append(sql, vals) 446: else 447: literal_append(sql, vals) 448: end 449: sql << PAREN_CLOSE 450: end 451: else 452: sql << PAREN_OPEN 453: literal_append(sql, cols) 454: sql << SPACE << op.to_s << SPACE 455: literal_append(sql, vals) 456: sql << PAREN_CLOSE 457: end 458: when *TWO_ARITY_OPERATORS 459: sql << PAREN_OPEN 460: literal_append(sql, args.at(0)) 461: sql << SPACE << op.to_s << SPACE 462: literal_append(sql, args.at(1)) 463: sql << PAREN_CLOSE 464: when *N_ARITY_OPERATORS 465: sql << PAREN_OPEN 466: c = false 467: op_str = " #{op} " 468: args.each do |a| 469: sql << op_str if c 470: literal_append(sql, a) 471: c ||= true 472: end 473: sql << PAREN_CLOSE 474: when :NOT 475: sql << NOT_SPACE 476: literal_append(sql, args.at(0)) 477: when :NOOP 478: literal_append(sql, args.at(0)) 479: when :'B~' 480: sql << TILDE 481: literal_append(sql, args.at(0)) 482: when :extract 483: sql << EXTRACT << args.at(0).to_s << FROM 484: literal_append(sql, args.at(1)) 485: sql << PAREN_CLOSE 486: else 487: raise(InvalidOperation, "invalid operator #{op}") 488: end 489: end
SQL fragment for constants
# File lib/sequel/dataset/sql.rb, line 492 492: def constant_sql_append(sql, constant) 493: sql << constant.to_s 494: end
Returns the number of records in the dataset.
DB[:table].count # SELECT COUNT(*) AS count FROM table LIMIT 1 # => 3
# File lib/sequel/dataset/actions.rb, line 100 100: def count 101: aggregate_dataset.get{COUNT(:*){}.as(count)}.to_i 102: end
Add a mutation method to this dataset instance.
# File lib/sequel/dataset/mutation.rb, line 37 37: def def_mutation_method(*meths) 38: meths.each do |meth| 39: instance_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__) 40: end 41: end
Deletes the records in the dataset. The returned value should be number of records deleted, but that is adapter dependent.
DB[:table].delete # DELETE * FROM table # => 3
# File lib/sequel/dataset/actions.rb, line 109 109: def delete(&block) 110: sql = delete_sql 111: if uses_returning?(:delete) 112: returning_fetch_rows(sql, &block) 113: else 114: execute_dui(sql) 115: end 116: end
Returns a DELETE SQL query string. See delete.
dataset.filter{|o| o.price >= 100}.delete_sql # => "DELETE FROM items WHERE (price >= 100)"
# File lib/sequel/dataset/sql.rb, line 12 12: def delete_sql 13: return static_sql(opts[:sql]) if opts[:sql] 14: check_modification_allowed! 15: clause_sql(:delete) 16: end
Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. Raises an error if arguments are given and DISTINCT ON is not supported.
DB[:items].distinct # SQL: SELECT DISTINCT * FROM items DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
# File lib/sequel/dataset/query.rb, line 70 70: def distinct(*args) 71: raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on? 72: clone(:distinct => args) 73: end
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
DB[:table].each{|row| p row} # SELECT * FROM table
Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each:
# File lib/sequel/dataset/actions.rb, line 127 127: def each 128: if @opts[:graph] 129: graph_each{|r| yield r} 130: elsif row_proc = @row_proc 131: fetch_rows(select_sql){|r| yield row_proc.call(r)} 132: else 133: fetch_rows(select_sql){|r| yield r} 134: end 135: self 136: end
Yields a paginated dataset for each page and returns the receiver. Does a count to find the total number of records for this dataset.
# File lib/sequel/extensions/pagination.rb, line 20 20: def each_page(page_size) 21: raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] 22: record_count = count 23: total_pages = (record_count / page_size.to_f).ceil 24: (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)} 25: self 26: end
Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:
DB[:configs].where(:key=>'setting').each_server{|ds| ds.update(:value=>'new_value')}
# File lib/sequel/dataset/misc.rb, line 49 49: def each_server 50: db.servers.each{|s| yield server(s)} 51: end
Returns true if no records exist in the dataset, false otherwise
DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1 # => false
# File lib/sequel/dataset/actions.rb, line 142 142: def empty? 143: get(Sequel::SQL::AliasedExpression.new(1, :one)).nil? 144: end
Alias for ==
# File lib/sequel/dataset/misc.rb, line 40 40: def eql?(o) 41: self == o 42: end
Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
:alias | Use the given value as the from_self alias |
:all | Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur |
:from_self | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].except(DB[:other_items]) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1 DB[:items].except(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items EXCEPT ALL SELECT * FROM other_items DB[:items].except(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 92 92: def except(dataset, opts={}) 93: opts = {:all=>opts} unless opts.is_a?(Hash) 94: raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except? 95: raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all? 96: compound_clone(:except, dataset, opts) 97: end
Performs the inverse of Dataset#filter. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.
DB[:items].exclude(:category => 'software') # SELECT * FROM items WHERE (category != 'software') DB[:items].exclude(:category => 'software', :id=>3) # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
# File lib/sequel/dataset/query.rb, line 107 107: def exclude(*cond, &block) 108: _filter_or_exclude(true, @opts[:having] ? :having : :where, *cond, &block) 109: end
Inverts the given conditions and adds them to the HAVING clause.
DB[:items].select_group(:name).exclude_having{count(name) < 2} # SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)
# File lib/sequel/dataset/query.rb, line 115 115: def exclude_having(*cond, &block) 116: _filter_or_exclude(true, :having, *cond, &block) 117: end
Inverts the given conditions and adds them to the WHERE clause.
DB[:items].select_group(:name).exclude_where(:category => 'software') # SELECT * FROM items WHERE (category != 'software') DB[:items].select_group(:name). exclude_having{count(name) < 2}. exclude_where(:category => 'software') # SELECT name FROM items WHERE (category != 'software') # GROUP BY name HAVING (count(name) >= 2)
# File lib/sequel/dataset/query.rb, line 129 129: def exclude_where(*cond, &block) 130: _filter_or_exclude(true, :where, *cond, &block) 131: end
Returns an EXISTS clause for the dataset as a LiteralString.
DB.select(1).where(DB[:items].exists) # SELECT 1 WHERE (EXISTS (SELECT * FROM items))
# File lib/sequel/dataset/sql.rb, line 22 22: def exists 23: SQL::PlaceholderLiteralString.new(EXISTS, [self], true) 24: end
Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.
# File lib/sequel/adapters/mysql.rb, line 295 295: def fetch_rows(sql) 296: execute(sql) do |r| 297: i = 1 298: cps = db.conversion_procs 299: cols = r.fetch_fields.map do |f| 300: # Pretend tinyint is another integer type if its length is not 1, to 301: # avoid casting to boolean if Sequel::MySQL.convert_tinyint_to_bool 302: # is set. 303: type_proc = f.type == 1 && f.length != 1 ? cps[2] : cps[f.type] 304: [output_identifier(f.name), type_proc, i+=1] 305: end 306: @columns = cols.map{|c| c.first} 307: if opts[:split_multiple_result_sets] 308: s = [] 309: yield_rows(r, cols){|h| s << h} 310: yield s 311: else 312: yield_rows(r, cols){|h| yield h} 313: end 314: end 315: self 316: end
Executes a select query and fetches records, yielding each record to the supplied block. The yielded records should be hashes with symbol keys. This method should probably should not be called by user code, use each instead.
# File lib/sequel/dataset/actions.rb, line 150 150: def fetch_rows(sql) 151: raise NotImplemented, NOTIMPL_MSG 152: end
# File lib/sequel/adapters/oracle.rb, line 373 373: def fetch_rows(sql) 374: execute(sql) do |cursor| 375: offset = @opts[:offset] 376: rn = row_number_column 377: cps = db.conversion_procs 378: cols = columns = cursor.get_col_names.map{|c| output_identifier(c)} 379: metadata = cursor.column_metadata 380: cm = cols.zip(metadata).map{|c, m| [c, cps[m.data_type]]} 381: columns = cols.reject{|x| x == rn} if offset 382: @columns = columns 383: while r = cursor.fetch 384: row = {} 385: r.zip(cm).each{|v, (c, cp)| row[c] = ((v && cp) ? cp.call(v) : v)} 386: row.delete(rn) if offset 387: yield row 388: end 389: end 390: self 391: end
Yield all rows returned by executing the given SQL and converting the types.
# File lib/sequel/adapters/postgres.rb, line 564 564: def fetch_rows(sql) 565: return cursor_fetch_rows(sql){|h| yield h} if @opts[:cursor] 566: execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res)){|h| yield h}} 567: end
Returns a copy of the dataset with the given conditions imposed upon it. If the query already has a HAVING clause, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause.
filter accepts the following argument types:
Hash - list of equality/inclusion expressions
Array - depends:
If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
Otherwise, treats each argument as a separate condition.
String - taken literally
Symbol - taken as a boolean column argument (e.g. WHERE active)
Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel expression filter DSL.
filter also takes a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the "Virtual Rows" guide
If both a block and regular argument are provided, they get ANDed together.
Examples:
DB[:items].filter(:id => 3) # SELECT * FROM items WHERE (id = 3) DB[:items].filter('price < ?', 100) # SELECT * FROM items WHERE price < 100 DB[:items].filter([[:id, [1,2,3]], [:id, 0..10]]) # SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10))) DB[:items].filter('price < 100') # SELECT * FROM items WHERE price < 100 DB[:items].filter(:active) # SELECT * FROM items WHERE :active DB[:items].filter{price < 100} # SELECT * FROM items WHERE (price < 100)
Multiple filter calls can be chained for scoping:
software = dataset.filter(:category => 'software').filter{price < 100} # SELECT * FROM items WHERE ((category = 'software') AND (price < 100))
See the the "Dataset Filtering" guide for more examples and details.
# File lib/sequel/dataset/query.rb, line 185 185: def filter(*cond, &block) 186: _filter(@opts[:having] ? :having : :where, *cond, &block) 187: end
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything. Examples:
DB[:table].first # SELECT * FROM table LIMIT 1 # => {:id=>7} DB[:table].first(2) # SELECT * FROM table LIMIT 2 # => [{:id=>6}, {:id=>4}] DB[:table].first(:id=>2) # SELECT * FROM table WHERE (id = 2) LIMIT 1 # => {:id=>2} DB[:table].first("id = 3") # SELECT * FROM table WHERE (id = 3) LIMIT 1 # => {:id=>3} DB[:table].first("id = ?", 4) # SELECT * FROM table WHERE (id = 4) LIMIT 1 # => {:id=>4} DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1 # => {:id=>5} DB[:table].first("id > ?", 4){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1 # => {:id=>5} DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2 # => [{:id=>1}]
# File lib/sequel/dataset/actions.rb, line 184 184: def first(*args, &block) 185: ds = block ? filter(&block) : self 186: 187: if args.empty? 188: ds.single_record 189: else 190: args = (args.size == 1) ? args.first : args 191: if Integer === args 192: ds.limit(args).all 193: else 194: ds.filter(args).single_record 195: end 196: end 197: end
Alias of first_source_alias
# File lib/sequel/dataset/misc.rb, line 54 54: def first_source 55: first_source_alias 56: end
The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an Error. If the table is aliased, returns the aliased name.
DB[:table].first_source_alias # => :table DB[:table___t].first_source_alias # => :t
# File lib/sequel/dataset/misc.rb, line 66 66: def first_source_alias 67: source = @opts[:from] 68: if source.nil? || source.empty? 69: raise Error, 'No source specified for query' 70: end 71: case s = source.first 72: when SQL::AliasedExpression 73: s.aliaz 74: when Symbol 75: sch, table, aliaz = split_symbol(s) 76: aliaz ? aliaz.to_sym : s 77: else 78: s 79: end 80: end
The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an error. If the table is aliased, returns the original table, not the alias
DB[:table].first_source_table # => :table DB[:table___t].first_source_table # => :table
# File lib/sequel/dataset/misc.rb, line 91 91: def first_source_table 92: source = @opts[:from] 93: if source.nil? || source.empty? 94: raise Error, 'No source specified for query' 95: end 96: case s = source.first 97: when SQL::AliasedExpression 98: s.expression 99: when Symbol 100: sch, table, aliaz = split_symbol(s) 101: aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s 102: else 103: s 104: end 105: end
Returns a cloned dataset with a :update lock style.
DB[:table].for_update # SELECT * FROM table FOR UPDATE
# File lib/sequel/dataset/query.rb, line 192 192: def for_update 193: lock_style(:update) 194: end
Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables.
DB[:items].from # SQL: SELECT * DB[:items].from(:blah) # SQL: SELECT * FROM blah DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
# File lib/sequel/dataset/query.rb, line 203 203: def from(*source) 204: table_alias_num = 0 205: sources = [] 206: ctes = nil 207: source.each do |s| 208: case s 209: when Hash 210: s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)} 211: when Dataset 212: if hoist_cte?(s) 213: ctes ||= [] 214: ctes += s.opts[:with] 215: s = s.clone(:with=>nil) 216: end 217: sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1)) 218: when Symbol 219: sch, table, aliaz = split_symbol(s) 220: if aliaz 221: s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table) 222: sources << SQL::AliasedExpression.new(s, aliaz.to_sym) 223: else 224: sources << s 225: end 226: else 227: sources << s 228: end 229: end 230: o = {:from=>sources.empty? ? nil : sources} 231: o[:with] = (opts[:with] || []) + ctes if ctes 232: o[:num_dataset_sources] = table_alias_num if table_alias_num > 0 233: clone(o) 234: end
Returns a dataset selecting from the current dataset. Supplying the :alias option controls the alias of the result.
ds = DB[:items].order(:name).select(:id, :name) # SELECT id,name FROM items ORDER BY name ds.from_self # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1 ds.from_self(:alias=>:foo) # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo
# File lib/sequel/dataset/query.rb, line 247 247: def from_self(opts={}) 248: fs = {} 249: @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)} 250: clone(fs).from(opts[:alias] ? as(opts[:alias]) : self) 251: end
Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.
DB[:table].get(:id) # SELECT id FROM table LIMIT 1 # => 3 ds.get{sum(id)} # SELECT sum(id) FROM table LIMIT 1 # => 6
# File lib/sequel/dataset/actions.rb, line 207 207: def get(column=(no_arg=true; nil), &block) 208: if block 209: raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg 210: select(&block).single_value 211: else 212: select(column).single_value 213: end 214: end
Allows you to join multiple datasets/tables and have the result set split into component tables.
This differs from the usual usage of join, which returns the result set as a single hash. For example:
# CREATE TABLE artists (id INTEGER, name TEXT); # CREATE TABLE albums (id INTEGER, name TEXT, artist_id INTEGER); DB[:artists].left_outer_join(:albums, :artist_id=>:id).first #=> {:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id} DB[:artists].graph(:albums, :artist_id=>:id).first #=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>{:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}}
Using a join such as left_outer_join, the attribute names that are shared between the tables are combined in the single return hash. You can get around that by using select with correct aliases for all of the columns, but it is simpler to use graph and have the result set split for you. In addition, graph respects any row_proc of the current dataset and the datasets you use with graph.
If you are graphing a table and all columns for that table are nil, this indicates that no matching rows existed in the table, so graph will return nil instead of a hash with all nil values:
# If the artist doesn't have any albums DB[:artists].graph(:albums, :artist_id=>:id).first => {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>nil}
Arguments:
dataset | Can be a symbol (specifying a table), another dataset, or an object that responds to dataset and returns a symbol or a dataset |
join_conditions | Any condition(s) allowed by join_table. |
block | A block that is passed to join_table. |
Options:
:from_self_alias | The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use. |
:implicit_qualifier | The qualifier of implicit conditions, see #. |
:join_type | The type of join to use (passed to join_table). Defaults to :left_outer. |
:select | An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table. |
:table_alias | The alias to use for the table. If not specified, doesn’t alias the table. You will get an error if the the alias (or table) name is used more than once. |
# File lib/sequel/dataset/graph.rb, line 74 74: def graph(dataset, join_conditions = nil, options = {}, &block) 75: # Allow the use of a model, dataset, or symbol as the first argument 76: # Find the table name/dataset based on the argument 77: dataset = dataset.dataset if dataset.respond_to?(:dataset) 78: table_alias = options[:table_alias] 79: case dataset 80: when Symbol 81: table = dataset 82: dataset = @db[dataset] 83: table_alias ||= table 84: when ::Sequel::Dataset 85: if dataset.simple_select_all? 86: table = dataset.opts[:from].first 87: table_alias ||= table 88: else 89: table = dataset 90: table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1) 91: end 92: else 93: raise Error, "The dataset argument should be a symbol, dataset, or model" 94: end 95: 96: # Raise Sequel::Error with explanation that the table alias has been used 97: raise_alias_error = lambda do 98: raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 99: end 100: 101: # Only allow table aliases that haven't been used 102: raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) 103: 104: # Use a from_self if this is already a joined table 105: ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self 106: 107: # Join the table early in order to avoid cloning the dataset twice 108: ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], &block) 109: opts = ds.opts 110: 111: # Whether to include the table in the result set 112: add_table = options[:select] == false ? false : true 113: # Whether to add the columns to the list of column aliases 114: add_columns = !ds.opts.include?(:graph_aliases) 115: 116: # Setup the initial graph data structure if it doesn't exist 117: if graph = opts[:graph] 118: opts[:graph] = graph = graph.dup 119: select = opts[:select].dup 120: [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup} 121: else 122: master = alias_symbol(ds.first_source_alias) 123: raise_alias_error.call if master == table_alias 124: # Master hash storing all .graph related information 125: graph = opts[:graph] = {} 126: # Associates column aliases back to tables and columns 127: column_aliases = graph[:column_aliases] = {} 128: # Associates table alias (the master is never aliased) 129: table_aliases = graph[:table_aliases] = {master=>self} 130: # Keep track of the alias numbers used 131: ca_num = graph[:column_alias_num] = Hash.new(0) 132: # All columns in the master table are never 133: # aliased, but are not included if set_graph_aliases 134: # has been used. 135: if add_columns 136: if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll))) 137: select = select.each do |sel| 138: column = case sel 139: when Symbol 140: _, c, a = split_symbol(sel) 141: (a || c).to_sym 142: when SQL::Identifier 143: sel.value.to_sym 144: when SQL::QualifiedIdentifier 145: column = sel.column 146: column = column.value if column.is_a?(SQL::Identifier) 147: column.to_sym 148: when SQL::AliasedExpression 149: column = sel.aliaz 150: column = column.value if column.is_a?(SQL::Identifier) 151: column.to_sym 152: else 153: raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" 154: end 155: column_aliases[column] = [master, column] 156: end 157: select = qualified_expression(select, master) 158: else 159: select = columns.map do |column| 160: column_aliases[column] = [master, column] 161: SQL::QualifiedIdentifier.new(master, column) 162: end 163: end 164: end 165: end 166: 167: # Add the table alias to the list of aliases 168: # Even if it isn't been used in the result set, 169: # we add a key for it with a nil value so we can check if it 170: # is used more than once 171: table_aliases = graph[:table_aliases] 172: table_aliases[table_alias] = add_table ? dataset : nil 173: 174: # Add the columns to the selection unless we are ignoring them 175: if add_table && add_columns 176: column_aliases = graph[:column_aliases] 177: ca_num = graph[:column_alias_num] 178: # Which columns to add to the result set 179: cols = options[:select] || dataset.columns 180: # If the column hasn't been used yet, don't alias it. 181: # If it has been used, try table_column. 182: # If that has been used, try table_column_N 183: # using the next value of N that we know hasn't been 184: # used 185: cols.each do |column| 186: col_alias, identifier = if column_aliases[column] 187: column_alias = :"#{table_alias}_#{column}" 188: if column_aliases[column_alias] 189: column_alias_num = ca_num[column_alias] 190: column_alias = :"#{column_alias}_#{column_alias_num}" 191: ca_num[column_alias] += 1 192: end 193: [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)] 194: else 195: ident = SQL::QualifiedIdentifier.new(table_alias, column) 196: [column, ident] 197: end 198: column_aliases[col_alias] = [table_alias, column] 199: select.push(identifier) 200: end 201: end 202: add_columns ? ds.select(*select) : ds 203: end
Don’t allow graphing a dataset that splits multiple statements
# File lib/sequel/adapters/mysql.rb, line 319 319: def graph(*) 320: raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets] 321: super 322: end
Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.
Options (all are boolean):
:all_columns | All columns must be matched to any of the given patterns. |
:all_patterns | All patterns must match at least one of the columns. |
:case_insensitive | Use a case insensitive pattern match (the default is case sensitive if the database supports it). |
If both :all_columns and :all_patterns are true, all columns must match all patterns.
Examples:
dataset.grep(:a, '%test%') # SELECT * FROM items WHERE (a LIKE '%test%') dataset.grep([:a, :b], %w'%test% foo') # SELECT * FROM items WHERE ((a LIKE '%test%') OR (a LIKE 'foo') OR (b LIKE '%test%') OR (b LIKE 'foo')) dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true) # SELECT * FROM a WHERE (((a LIKE '%foo%') OR (b LIKE '%foo%')) AND ((a LIKE '%bar%') OR (b LIKE '%bar%'))) dataset.grep([:a, :b], %w'%foo% %bar%', :all_columns=>true) # SELECT * FROM a WHERE (((a LIKE '%foo%') OR (a LIKE '%bar%')) AND ((b LIKE '%foo%') OR (b LIKE '%bar%'))) dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true, :all_columns=>true) # SELECT * FROM a WHERE ((a LIKE '%foo%') AND (b LIKE '%foo%') AND (a LIKE '%bar%') AND (b LIKE '%bar%'))
# File lib/sequel/dataset/query.rb, line 284 284: def grep(columns, patterns, opts={}) 285: if opts[:all_patterns] 286: conds = Array(patterns).map do |pat| 287: SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)}) 288: end 289: filter(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds)) 290: else 291: conds = Array(columns).map do |c| 292: SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)}) 293: end 294: filter(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds)) 295: end 296: end
Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to filter.
DB[:items].group(:id) # SELECT * FROM items GROUP BY id DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
# File lib/sequel/dataset/query.rb, line 305 305: def group(*columns, &block) 306: virtual_row_columns(columns, block) 307: clone(:group => (columns.compact.empty? ? nil : columns)) 308: end
Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to filter.
Examples:
DB[:items].group_and_count(:name).all # SELECT name, count(*) AS count FROM items GROUP BY name # => [{:name=>'a', :count=>1}, ...] DB[:items].group_and_count(:first_name, :last_name).all # SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name # => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...] DB[:items].group_and_count(:first_name___name).all # SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name # => [{:name=>'a', :count=>1}, ...] DB[:items].group_and_count{substr(first_name, 1, 1).as(initial)}.all # SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1) # => [{:initial=>'a', :count=>1}, ...]
# File lib/sequel/dataset/query.rb, line 336 336: def group_and_count(*columns, &block) 337: select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT) 338: end
Alias of group
# File lib/sequel/dataset/query.rb, line 311 311: def group_by(*columns, &block) 312: group(*columns, &block) 313: end
Adds the appropriate CUBE syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 341 341: def group_cube 342: raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube? 343: clone(:group_options=>:cube) 344: end
Adds the appropriate ROLLUP syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 347 347: def group_rollup 348: raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup? 349: clone(:group_options=>:rollup) 350: end
Define a hash value such that datasets with the same DB, opts, and SQL will have the same hash value
# File lib/sequel/dataset/misc.rb, line 109 109: def hash 110: [db, opts.sort_by{|k, v| k.to_s}, sql].hash 111: end
Returns a copy of the dataset with the HAVING conditions changed. See # for argument types.
DB[:items].group(:sum).having(:sum=>10) # SELECT * FROM items GROUP BY sum HAVING (sum = 10)
# File lib/sequel/dataset/query.rb, line 356 356: def having(*cond, &block) 357: _filter(:having, *cond, &block) 358: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 115 115: def identifier_input_method 116: if defined?(@identifier_input_method) 117: @identifier_input_method 118: elsif db.respond_to?(:identifier_input_method) 119: @identifier_input_method = db.identifier_input_method 120: else 121: @identifier_input_method = nil 122: end 123: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 127 127: def identifier_output_method 128: if defined?(@identifier_output_method) 129: @identifier_output_method 130: elsif db.respond_to?(:identifier_output_method) 131: @identifier_output_method = db.identifier_output_method 132: else 133: @identifier_output_method = nil 134: end 135: end
Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction.
This method is called with a columns array and an array of value arrays:
DB[:table].import([:x, :y], [[1, 2], [3, 4]]) # INSERT INTO table (x, y) VALUES (1, 2) # INSERT INTO table (x, y) VALUES (3, 4)
This method also accepts a dataset instead of an array of value arrays:
DB[:table].import([:x, :y], DB[:table2].select(:a, :b)) # INSERT INTO table (x, y) SELECT a, b FROM table2
Options:
:commit_every | Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records. |
:server | Set the server/shard to use for the transaction and insert queries. |
:slice | Same as :commit_every, :commit_every takes precedence. |
# File lib/sequel/dataset/actions.rb, line 239 239: def import(columns, values, opts={}) 240: return @db.transaction{insert(columns, values)} if values.is_a?(Dataset) 241: 242: return if values.empty? 243: raise(Error, IMPORT_ERROR_MSG) if columns.empty? 244: ds = opts[:server] ? server(opts[:server]) : self 245: 246: if slice_size = opts[:commit_every] || opts[:slice] 247: offset = 0 248: rows = [] 249: while offset < values.length 250: rows << ds._import(columns, values[offset, slice_size], opts) 251: offset += slice_size 252: end 253: rows.flatten 254: else 255: ds._import(columns, values, opts) 256: end 257: end
Inserts values into the associated table. The returned value is generally the value of the primary key for the inserted row, but that is adapter dependent.
insert handles a number of different argument formats:
no arguments or single empty hash | |
single hash | Most common format, treats keys as columns an values as values |
single array | Treats entries as values, with no columns |
two arrays | Treats first array as columns, second array as values |
single Dataset | Treats as an insert based on a selection from the dataset given, with no columns |
array and dataset | Treats as an insert based on a selection from the dataset given, with the columns given by the array. |
Examples:
DB[:items].insert # INSERT INTO items DEFAULT VALUES DB[:items].insert({}) # INSERT INTO items DEFAULT VALUES DB[:items].insert([1,2,3]) # INSERT INTO items VALUES (1, 2, 3) DB[:items].insert([:a, :b], [1,2]) # INSERT INTO items (a, b) VALUES (1, 2) DB[:items].insert(:a => 1, :b => 2) # INSERT INTO items (a, b) VALUES (1, 2) DB[:items].insert(DB[:old_items]) # INSERT INTO items SELECT * FROM old_items DB[:items].insert([:a, :b], DB[:old_items]) # INSERT INTO items (a, b) SELECT * FROM old_items
# File lib/sequel/dataset/actions.rb, line 294 294: def insert(*values, &block) 295: sql = insert_sql(*values) 296: if uses_returning?(:insert) 297: returning_fetch_rows(sql, &block) 298: else 299: execute_insert(sql) 300: end 301: end
Inserts multiple values. If a block is given it is invoked for each item in the given array before inserting it. See multi_insert as a possibly faster version that may be able to insert multiple records in one SQL statement (if supported by the database). Returns an array of primary keys of inserted rows.
DB[:table].insert_multiple([{:x=>1}, {:x=>2}]) # => [4, 5] # INSERT INTO table (x) VALUES (1) # INSERT INTO table (x) VALUES (2) DB[:table].insert_multiple([{:x=>1}, {:x=>2}]){|row| row[:y] = row[:x] * 2} # => [6, 7] # INSERT INTO table (x, y) VALUES (1, 2) # INSERT INTO table (x, y) VALUES (2, 4)
# File lib/sequel/dataset/actions.rb, line 318 318: def insert_multiple(array, &block) 319: if block 320: array.map{|i| insert(block.call(i))} 321: else 322: array.map{|i| insert(i)} 323: end 324: end
Returns an INSERT SQL query string. See insert.
DB[:items].insert_sql(:a=>1) # => "INSERT INTO items (a) VALUES (1)"
# File lib/sequel/dataset/sql.rb, line 30 30: def insert_sql(*values) 31: return static_sql(@opts[:sql]) if @opts[:sql] 32: 33: check_modification_allowed! 34: 35: columns = [] 36: 37: case values.size 38: when 0 39: return insert_sql({}) 40: when 1 41: case vals = values.at(0) 42: when Hash 43: vals = @opts[:defaults].merge(vals) if @opts[:defaults] 44: vals = vals.merge(@opts[:overrides]) if @opts[:overrides] 45: values = [] 46: vals.each do |k,v| 47: columns << k 48: values << v 49: end 50: when Dataset, Array, LiteralString 51: values = vals 52: else 53: if vals.respond_to?(:values) && (v = vals.values).is_a?(Hash) 54: return insert_sql(v) 55: end 56: end 57: when 2 58: if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString)) 59: columns, values = v0, v1 60: raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length 61: end 62: end 63: 64: if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 65: columns = [columns().last] 66: values = [DEFAULT] 67: end 68: clone(:columns=>columns, :values=>values)._insert_sql 69: end
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
# File lib/sequel/dataset/misc.rb, line 139 139: def inspect 140: c = self.class 141: c = c.superclass while c.name.nil? || c.name == '' 142: "#<#{c.name}: #{sql.inspect}>" 143: end
Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
:alias | Use the given value as the from_self alias |
:all | Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur |
:from_self | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].intersect(DB[:other_items]) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1 DB[:items].intersect(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items INTERSECT ALL SELECT * FROM other_items DB[:items].intersect(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 377 377: def intersect(dataset, opts={}) 378: opts = {:all=>opts} unless opts.is_a?(Hash) 379: raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except? 380: raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all? 381: compound_clone(:intersect, dataset, opts) 382: end
Returns the interval between minimum and maximum values for the given column.
DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1 # => 6
# File lib/sequel/dataset/actions.rb, line 331 331: def interval(column) 332: aggregate_dataset.get{max(column) - min(column)} 333: end
Inverts the current filter.
DB[:items].filter(:category => 'software').invert # SELECT * FROM items WHERE (category != 'software') DB[:items].filter(:category => 'software', :id=>3).invert # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
# File lib/sequel/dataset/query.rb, line 391 391: def invert 392: having, where = @opts[:having], @opts[:where] 393: raise(Error, "No current filter") unless having || where 394: o = {} 395: o[:having] = SQL::BooleanExpression.invert(having) if having 396: o[:where] = SQL::BooleanExpression.invert(where) if where 397: clone(o) 398: end
Alias of inner_join
# File lib/sequel/dataset/query.rb, line 401 401: def join(*args, &block) 402: inner_join(*args, &block) 403: end
SQL fragment specifying a JOIN clause without ON or USING.
# File lib/sequel/dataset/sql.rb, line 508 508: def join_clause_sql_append(sql, jc) 509: table = jc.table 510: table_alias = jc.table_alias 511: table_alias = nil if table == table_alias 512: sql << SPACE << join_type_sql(jc.join_type) << SPACE 513: identifier_append(sql, table) 514: as_sql_append(sql, table_alias) if table_alias 515: end
Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.
Takes the following arguments:
type - The type of join to do (e.g. :inner)
table - Depends on type:
Dataset - a subselect is performed with an alias of tN for some value of N
Model (or anything responding to :table_name) - table.table_name
String, Symbol: table
expr - specifies conditions, depends on type:
Hash, Array of two element arrays - Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.
Array - If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.
options - a hash of options, with any of the following keys:
:table_alias - the name of the table’s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
:implicit_qualifier - The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.
block - The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike filter, this block is not treated as a virtual row block.
Examples:
DB[:a].join_table(:cross, :b) # SELECT * FROM a CROSS JOIN b DB[:a].join_table(:inner, DB[:b], :c=>d) # SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d) DB[:a].join_table(:left, :b___c, [:d]) # SELECT * FROM a LEFT JOIN b AS c USING (d) DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js| (:d.qualify(ta) > :e.qualify(jta)) & {:f.qualify(ta)=>DB.from(js.first.table).select(:g)} end # SELECT * FROM a NATURAL JOIN b INNER JOIN c # ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
# File lib/sequel/dataset/query.rb, line 456 456: def join_table(type, table, expr=nil, options={}, &block) 457: if hoist_cte?(table) 458: s, ds = hoist_cte(table) 459: return s.join_table(type, ds, expr, options, &block) 460: end 461: 462: using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)} 463: if using_join && !supports_join_using? 464: h = {} 465: expr.each{|s| h[s] = s} 466: return join_table(type, table, h, options) 467: end 468: 469: case options 470: when Hash 471: table_alias = options[:table_alias] 472: last_alias = options[:implicit_qualifier] 473: when Symbol, String, SQL::Identifier 474: table_alias = options 475: last_alias = nil 476: else 477: raise Error, "invalid options format for join_table: #{options.inspect}" 478: end 479: 480: if Dataset === table 481: if table_alias.nil? 482: table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 483: table_alias = dataset_alias(table_alias_num) 484: end 485: table_name = table_alias 486: else 487: table = table.table_name if table.respond_to?(:table_name) 488: table, implicit_table_alias = split_alias(table) 489: table_alias ||= implicit_table_alias 490: table_name = table_alias || table 491: end 492: 493: join = if expr.nil? and !block 494: SQL::JoinClause.new(type, table, table_alias) 495: elsif using_join 496: raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block 497: SQL::JoinUsingClause.new(expr, type, table, table_alias) 498: else 499: last_alias ||= @opts[:last_joined_table] || first_source_alias 500: if Sequel.condition_specifier?(expr) 501: expr = expr.collect do |k, v| 502: k = qualified_column_name(k, table_name) if k.is_a?(Symbol) 503: v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) 504: [k,v] 505: end 506: expr = SQL::BooleanExpression.from_value_pairs(expr) 507: end 508: if block 509: expr2 = yield(table_name, last_alias, @opts[:join] || []) 510: expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 511: end 512: SQL::JoinOnClause.new(expr, type, table, table_alias) 513: end 514: 515: opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name} 516: opts[:num_dataset_sources] = table_alias_num if table_alias_num 517: clone(opts) 518: end
Reverses the order and then runs # with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.
DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1 # => {:id=>10} DB[:table].order(:id.desc).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2 # => [{:id=>1}, {:id=>2}]
# File lib/sequel/dataset/actions.rb, line 345 345: def last(*args, &block) 346: raise(Error, 'No order specified') unless @opts[:order] 347: reverse.first(*args, &block) 348: end
If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.
DB[:items].limit(10) # SELECT * FROM items LIMIT 10 DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20 DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10 DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10 DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
# File lib/sequel/dataset/query.rb, line 537 537: def limit(l, o = nil) 538: return from_self.limit(l, o) if @opts[:sql] 539: 540: if Range === l 541: o = l.first 542: l = l.last - l.first + (l.exclude_end? ? 0 : 1) 543: end 544: l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString) 545: if l.is_a?(Integer) 546: raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 547: end 548: opts = {:limit => l} 549: if o 550: o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString) 551: if o.is_a?(Integer) 552: raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 553: end 554: opts[:offset] = o 555: end 556: clone(opts) 557: end
Returns a literal representation of a value to be used as part of an SQL expression.
DB[:items].literal("abc'def\\") #=> "'abc''def\\\\'" DB[:items].literal(:items__id) #=> "items.id" DB[:items].literal([1, 2, 3]) => "(1, 2, 3)" DB[:items].literal(DB[:items]) => "(SELECT * FROM items)" DB[:items].literal(:x + 1 > :y) => "((x + 1) > y)"
If an unsupported object is given, an Error is raised.
# File lib/sequel/dataset/sql.rb, line 81 81: def literal_append(sql, v) 82: case v 83: when Symbol 84: literal_symbol_append(sql, v) 85: when String 86: case v 87: when LiteralString 88: sql << v 89: when SQL::Blob 90: literal_blob_append(sql, v) 91: else 92: literal_string_append(sql, v) 93: end 94: when Integer 95: sql << literal_integer(v) 96: when Hash 97: literal_hash_append(sql, v) 98: when SQL::Expression 99: literal_expression_append(sql, v) 100: when Float 101: sql << literal_float(v) 102: when BigDecimal 103: sql << literal_big_decimal(v) 104: when NilClass 105: sql << literal_nil 106: when TrueClass 107: sql << literal_true 108: when FalseClass 109: sql << literal_false 110: when Array 111: literal_array_append(sql, v) 112: when Time 113: sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v)) 114: when DateTime 115: sql << literal_datetime(v) 116: when Date 117: sql << literal_date(v) 118: when Dataset 119: literal_dataset_append(sql, v) 120: else 121: literal_other_append(sql, v) 122: end 123: end
Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. Otherwise, a symbol may be used for database independent locking. Currently :update is respected by most databases, and :share is supported by some.
DB[:items].lock_style('FOR SHARE') # SELECT * FROM items FOR SHARE
# File lib/sequel/dataset/query.rb, line 565 565: def lock_style(style) 566: clone(:lock => style) 567: end
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.
DB[:table].map(:id) # SELECT * FROM table # => [1, 2, 3, ...] DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table # => [2, 4, 6, ...]
You can also provide an array of column names:
DB[:table].map([:id, :name]) # SELECT * FROM table # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
# File lib/sequel/dataset/actions.rb, line 364 364: def map(column=nil, &block) 365: if column 366: raise(Error, ARG_BLOCK_ERROR_MSG) if block 367: return naked.map(column) if row_proc 368: if column.is_a?(Array) 369: super(){|r| r.values_at(*column)} 370: else 371: super(){|r| r[column]} 372: end 373: else 374: super(&block) 375: end 376: end
Returns the maximum value for the given column.
DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1 # => 10
# File lib/sequel/dataset/actions.rb, line 382 382: def max(column) 383: aggregate_dataset.get{max(column)} 384: end
Returns the minimum value for the given column.
DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 390 390: def min(column) 391: aggregate_dataset.get{min(column)} 392: end
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:
DB[:table].multi_insert([{:x => 1}, {:x => 2}]) # INSERT INTO table (x) VALUES (1) # INSERT INTO table (x) VALUES (2)
Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.
This respects the same options as #.
# File lib/sequel/dataset/actions.rb, line 406 406: def multi_insert(hashes, opts={}) 407: return if hashes.empty? 408: columns = hashes.first.keys 409: import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts) 410: end
Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.
This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.
# File lib/sequel/dataset/sql.rb, line 131 131: def multi_insert_sql(columns, values) 132: values.map{|r| insert_sql(columns, r)} 133: end
Returns a cloned dataset without a row_proc.
ds = DB[:items] ds.row_proc = proc{|r| r.invert} ds.all # => [{2=>:id}] ds.naked.all # => [{:id=>2}]
# File lib/sequel/dataset/query.rb, line 575 575: def naked 576: ds = clone 577: ds.row_proc = nil 578: ds 579: end
Remove the row_proc from the current dataset.
# File lib/sequel/dataset/mutation.rb, line 44 44: def naked! 45: self.row_proc = nil 46: self 47: end
SQL fragment for NegativeBooleanConstants
# File lib/sequel/dataset/sql.rb, line 533 533: def negative_boolean_constant_sql_append(sql, constant) 534: sql << NOT_SPACE 535: boolean_constant_sql_append(sql, constant) 536: end
Return a cloned nullified dataset.
# File lib/sequel/extensions/null_dataset.rb, line 81 81: def nullify 82: clone.nullify! 83: end
Nullify the current dataset
# File lib/sequel/extensions/null_dataset.rb, line 86 86: def nullify! 87: extend NullDataset 88: end
Adds an alternate filter to an existing filter using OR. If no filter exists an Error is raised.
DB[:items].filter(:a).or(:b) # SELECT * FROM items WHERE a OR b
# File lib/sequel/dataset/query.rb, line 585 585: def or(*cond, &block) 586: clause = (@opts[:having] ? :having : :where) 587: raise(InvalidOperation, "No existing filter found.") unless @opts[clause] 588: cond = cond.first if cond.size == 1 589: clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block))) 590: end
Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to filter.
DB[:items].order(:name) # SELECT * FROM items ORDER BY name DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b DB[:items].order('a + b'.lit) # SELECT * FROM items ORDER BY a + b DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b) DB[:items].order(:name.desc) # SELECT * FROM items ORDER BY name DESC DB[:items].order(:name.asc(:nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC DB[:items].order(nil) # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 606 606: def order(*columns, &block) 607: virtual_row_columns(columns, block) 608: clone(:order => (columns.compact.empty?) ? nil : columns) 609: end
Alias of order_more, for naming consistency with order_prepend.
# File lib/sequel/dataset/query.rb, line 612 612: def order_append(*columns, &block) 613: order_more(*columns, &block) 614: end
Alias of order
# File lib/sequel/dataset/query.rb, line 617 617: def order_by(*columns, &block) 618: order(*columns, &block) 619: end
Returns a copy of the dataset with the order columns added to the end of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b DB[:items].order(:a).order_more(:b) # SELECT * FROM items ORDER BY a, b
# File lib/sequel/dataset/query.rb, line 626 626: def order_more(*columns, &block) 627: columns = @opts[:order] + columns if @opts[:order] 628: order(*columns, &block) 629: end
Returns a copy of the dataset with the order columns added to the beginning of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
# File lib/sequel/dataset/query.rb, line 636 636: def order_prepend(*columns, &block) 637: ds = order(*columns, &block) 638: @opts[:order] ? ds.order_more(*@opts[:order]) : ds 639: end
SQL fragment for the ordered expression, used in the ORDER BY clause.
# File lib/sequel/dataset/sql.rb, line 540 540: def ordered_expression_sql_append(sql, oe) 541: literal_append(sql, oe.expression) 542: sql << (oe.descending ? DESC : ASC) 543: case oe.nulls 544: when :first 545: sql << NULLS_FIRST 546: when :last 547: sql << NULLS_LAST 548: end 549: end
Returns a paginated dataset. The returned dataset is limited to the page size at the correct offset, and extended with the Pagination module. If a record count is not provided, does a count of total number of records for this dataset.
# File lib/sequel/extensions/pagination.rb, line 11 11: def paginate(page_no, page_size, record_count=nil) 12: raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] 13: paginated = limit(page_size, (page_no - 1) * page_size) 14: paginated.extend(Pagination) 15: paginated.set_pagination_info(page_no, page_size, record_count || count) 16: end
SQL fragment for a literal string with placeholders
# File lib/sequel/dataset/sql.rb, line 552 552: def placeholder_literal_string_sql_append(sql, pls) 553: args = pls.args 554: str = pls.str 555: sql << PAREN_OPEN if pls.parens 556: if args.is_a?(Hash) 557: re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/ 558: loop do 559: previous, q, str = str.partition(re) 560: sql << previous 561: literal_append(sql, args[($1||q[1..1].to_s).to_sym]) unless q.empty? 562: break if str.empty? 563: end 564: elsif str.is_a?(Array) 565: len = args.length 566: str.each_with_index do |s, i| 567: sql << s 568: literal_append(sql, args[i]) unless i == len 569: end 570: else 571: i = 1 572: loop do 573: previous, q, str = str.partition(QUESTION_MARK) 574: sql << previous 575: literal_append(sql, args.at(i+=1)) unless q.empty? 576: break if str.empty? 577: end 578: end 579: sql << PAREN_CLOSE if pls.parens 580: end
Prepare the given type of statement with the given name, and store it in the database to be called later.
# File lib/sequel/adapters/postgres.rb, line 681 681: def prepare(type, name=nil, *values) 682: ps = to_prepared_statement(type, values) 683: ps.extend(PreparedStatementMethods) 684: if name 685: ps.prepared_statement_name = name 686: db.set_prepared_statement(name, ps) 687: end 688: ps 689: end
Prepare the given type of query with the given name and store it in the database. Note that a new native prepared statement is created on each call to this prepared statement.
# File lib/sequel/adapters/oracle.rb, line 396 396: def prepare(type, name=nil, *values) 397: ps = to_prepared_statement(type, values) 398: ps.extend(PreparedStatementMethods) 399: if name 400: ps.prepared_statement_name = name 401: db.set_prepared_statement(name, ps) 402: end 403: ps 404: end
Prepare an SQL statement for later execution. Takes a type similar to #, and the name symbol of the prepared statement. While name defaults to nil, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.
This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated database, where it can be called by name. The following usage is identical:
ps = DB[:table].filter(:name=>:$name).prepare(:first, :select_by_name) ps.call(:name=>'Blah') # SELECT * FROM table WHERE name = ? -- ('Blah') # => {:id=>1, :name=>'Blah'} DB.call(:select_by_name, :name=>'Blah') # Same thing
# File lib/sequel/dataset/prepared_statements.rb, line 250 250: def prepare(type, name=nil, *values) 251: ps = to_prepared_statement(type, values) 252: db.set_prepared_statement(name, ps) if name 253: ps 254: end
PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.
# File lib/sequel/adapters/postgres.rb, line 695 695: def prepared_arg_placeholder 696: PREPARED_ARG_PLACEHOLDER 697: end
Pretty prints the records in the dataset as plain-text table.
# File lib/sequel/extensions/pretty_table.rb, line 10 10: def print(*cols) 11: ds = naked 12: rows = ds.all 13: Sequel::PrettyTable.print(rows, cols.empty? ? ds.columns : cols) 14: end
Whether this dataset will provide accurate number of rows matched for delete and update statements. Accurate in this case is the number of rows matched by the dataset’s filter.
# File lib/sequel/dataset/features.rb, line 23 23: def provides_accurate_rows_matched? 24: true 25: end
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table). If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.
# File lib/sequel/dataset/sql.rb, line 586 586: def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) 587: identifier_append(sql, table) 588: sql << DOT 589: identifier_append(sql, column) 590: end
Qualify to the given table, or first source if no table is given.
DB[:items].filter(:id=>1).qualify # SELECT items.* FROM items WHERE (items.id = 1) DB[:items].filter(:id=>1).qualify(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 648 648: def qualify(table=first_source) 649: qualify_to(table) 650: end
Return a copy of the dataset with unqualified identifiers in the SELECT, WHERE, GROUP, HAVING, and ORDER clauses qualified by the given table. If no columns are currently selected, select all columns of the given table.
DB[:items].filter(:id=>1).qualify_to(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 659 659: def qualify_to(table) 660: o = @opts 661: return clone if o[:sql] 662: h = {} 663: (o.keys & QUALIFY_KEYS).each do |k| 664: h[k] = qualified_expression(o[k], table) 665: end 666: h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty? 667: clone(h) 668: end
Qualify the dataset to its current first source. This is useful if you have unqualified identifiers in the query that all refer to the first source, and you want to join to another table which has columns with the same name as columns in the current dataset. See qualify_to.
DB[:items].filter(:id=>1).qualify_to_first_source # SELECT items.* FROM items WHERE (items.id = 1)
# File lib/sequel/dataset/query.rb, line 678 678: def qualify_to_first_source 679: qualify_to(first_source) 680: end
Translates a query block into a dataset. Query blocks can be useful when expressing complex SELECT statements, e.g.:
dataset = DB[:items].query do select :x, :y, :z filter{|o| (o.x > 1) & (o.y > 2)} order :z.desc end
Which is the same as:
dataset = DB[:items].select(:x, :y, :z).filter{|o| (o.x > 1) & (o.y > 2)}.order(:z.desc)
Note that inside a call to query, you cannot call each, insert, update, or delete (or any method that calls those), or Sequel will raise an error.
# File lib/sequel/extensions/query.rb, line 30 30: def query(&block) 31: copy = clone({}) 32: copy.extend(QueryBlockCopy) 33: copy.instance_eval(&block) 34: clone(copy.opts) 35: end
Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.
# File lib/sequel/dataset/sql.rb, line 595 595: def quote_identifier_append(sql, name) 596: if name.is_a?(LiteralString) 597: sql << name 598: else 599: name = name.value if name.is_a?(SQL::Identifier) 600: name = input_identifier(name) 601: if quote_identifiers? 602: quoted_identifier_append(sql, name) 603: else 604: sql << name 605: end 606: end 607: end
Whether this dataset quotes identifiers.
# File lib/sequel/dataset/features.rb, line 10 10: def quote_identifiers? 11: if defined?(@quote_identifiers) 12: @quote_identifiers 13: elsif db.respond_to?(:quote_identifiers?) 14: @quote_identifiers = db.quote_identifiers? 15: else 16: @quote_identifiers = false 17: end 18: end
Separates the schema from the table and returns a string with them quoted (if quoting identifiers)
# File lib/sequel/dataset/sql.rb, line 611 611: def quote_schema_table_append(sql, table) 612: schema, table = schema_and_table(table) 613: if schema 614: quote_identifier_append(sql, schema) 615: sql << DOT 616: end 617: quote_identifier_append(sql, table) 618: end
This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).
# File lib/sequel/dataset/sql.rb, line 623 623: def quoted_identifier_append(sql, name) 624: sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE 625: end
Returns a Range instance made from the minimum and maximum values for the given column.
DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1 # => 1..10
# File lib/sequel/dataset/actions.rb, line 417 417: def range(column) 418: if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first 419: (r[:v1]..r[:v2]) 420: end 421: end
Whether you must use a column alias list for recursive CTEs (false by default).
# File lib/sequel/dataset/features.rb, line 29 29: def recursive_cte_requires_column_aliases? 30: false 31: end
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer)
# File lib/sequel/dataset/features.rb, line 41 41: def requires_placeholder_type_specifiers? 42: false 43: end
Oracle requires type specifiers for placeholders, at least if you ever want to use a nil/NULL value as the value for the placeholder.
# File lib/sequel/adapters/oracle.rb, line 409 409: def requires_placeholder_type_specifiers? 410: true 411: end
Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format).
# File lib/sequel/dataset/features.rb, line 35 35: def requires_sql_standard_datetimes? 36: false 37: end
Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.
DB[:items].returning # RETURNING * DB[:items].returning(nil) # RETURNING NULL DB[:items].returning(:id, :name) # RETURNING id, name
# File lib/sequel/dataset/query.rb, line 690 690: def returning(*values) 691: clone(:returning=>values) 692: end
Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.
DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC DB[:items].order(:id).reverse(:name.asc) # SELECT * FROM items ORDER BY name ASC
# File lib/sequel/dataset/query.rb, line 700 700: def reverse(*order) 701: order(*invert_order(order.empty? ? @opts[:order] : order)) 702: end
Alias of reverse
# File lib/sequel/dataset/query.rb, line 705 705: def reverse_order(*order) 706: reverse(*order) 707: end
The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies
# File lib/sequel/dataset/misc.rb, line 147 147: def row_number_column 148: :x_sequel_row_number_x 149: end
Split the schema information from the table
# File lib/sequel/dataset/sql.rb, line 628 628: def schema_and_table(table_name) 629: sch = db.default_schema if db 630: case table_name 631: when Symbol 632: s, t, a = split_symbol(table_name) 633: [s||sch, t] 634: when SQL::QualifiedIdentifier 635: [table_name.table, table_name.column] 636: when SQL::Identifier 637: [sch, table_name.value] 638: when String 639: [sch, table_name] 640: else 641: raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String' 642: end 643: end
Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to filter.
DB[:items].select(:a) # SELECT a FROM items DB[:items].select(:a, :b) # SELECT a, b FROM items DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
# File lib/sequel/dataset/query.rb, line 716 716: def select(*columns, &block) 717: virtual_row_columns(columns, block) 718: m = [] 719: columns.each do |i| 720: i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i 721: end 722: clone(:select => m) 723: end
Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.
DB[:items].select(:a).select_all # SELECT * FROM items DB[:items].select_all(:items) # SELECT items.* FROM items DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
# File lib/sequel/dataset/query.rb, line 732 732: def select_all(*tables) 733: if tables.empty? 734: clone(:select => nil) 735: else 736: select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)}) 737: end 738: end
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.
DB[:items].select(:a).select(:b) # SELECT b FROM items DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items DB[:items].select_append(:b) # SELECT *, b FROM items
# File lib/sequel/dataset/query.rb, line 747 747: def select_append(*columns, &block) 748: cur_sel = @opts[:select] 749: if !cur_sel || cur_sel.empty? 750: unless supports_select_all_and_column? 751: return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block) 752: end 753: cur_sel = [WILDCARD] 754: end 755: select(*(cur_sel + columns), &block) 756: end
Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to filter.
DB[:items].select_group(:a, :b) # SELECT a, b FROM items GROUP BY a, b DB[:items].select_group(:c___a){f(c2)} # SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
# File lib/sequel/dataset/query.rb, line 767 767: def select_group(*columns, &block) 768: virtual_row_columns(columns, block) 769: select(*columns).group(*columns.map{|c| unaliased_identifier(c)}) 770: end
Returns a hash with key_column values as keys and value_column values as values. Similar to to_hash, but only selects the columns given.
DB[:table].select_hash(:id, :name) # SELECT id, name FROM table # => {1=>'a', 2=>'b', ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table # {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the # method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 438 438: def select_hash(key_column, value_column) 439: _select_hash(:to_hash, key_column, value_column) 440: end
Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given.
DB[:table].select_hash(:name, :id) # SELECT id, name FROM table # => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash([:first, :middle], [:last, :id]) # SELECT * FROM table # {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the # method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 457 457: def select_hash_groups(key_column, value_column) 458: _select_hash(:to_hash_groups, key_column, value_column) 459: end
Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.
DB[:table].select_map(:id) # SELECT id FROM table # => [3, 5, 8, 1, ...] DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table # => [6, 10, 16, 2, ...]
You can also provide an array of column names:
DB[:table].select_map([:id, :name]) # SELECT id, name FROM table # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the # method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 481 481: def select_map(column=nil, &block) 482: _select_map(column, false, &block) 483: end
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected it will just select the columns given.
DB[:items].select(:a).select(:b) # SELECT b FROM items DB[:items].select(:a).select_more(:b) # SELECT a, b FROM items DB[:items].select_more(:b) # SELECT b FROM items
# File lib/sequel/dataset/query.rb, line 779 779: def select_more(*columns, &block) 780: columns = @opts[:select] + columns if @opts[:select] 781: select(*columns, &block) 782: end
The same as select_map, but in addition orders the array by the column.
DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id # => [1, 2, 3, 4, ...] DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2) # => [2, 4, 6, 8, ...]
You can also provide an array of column names:
DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the # method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 501 501: def select_order_map(column=nil, &block) 502: _select_map(column, true, &block) 503: end
Remove columns from the list of selected columns. If any of the currently selected columns use expressions/aliases, this will remove selected columns with the given aliases. It will also remove entries from the selection that match exactly:
# Assume columns a, b, and c in items table DB[:items] # SELECT * FROM items DB[:items].select_remove(:c) # SELECT a, b FROM items DB[:items].select(:a, :b___c, :c___b).select_remove(:c) # SELECT a, c AS b FROM items DB[:items].select(:a, :b___c, :c___b).select_remove(:c___b) # SELECT a, b AS c FROM items
Note that there are a few cases where this method may not work correctly:
This dataset joins multiple tables and does not have an existing explicit selection. In this case, the code will currently use unqualified column names for all columns the dataset returns, except for the columns given.
This dataset has an existing explicit selection containing an item that returns multiple database columns (e.g. :table.*, ‘column1, column2’.lit). In this case, the behavior is undefined and this method should not be used.
There may be other cases where this method does not work correctly, use it with caution.
# File lib/sequel/extensions/select_remove.rb, line 27 27: def select_remove(*cols) 28: if (sel = @opts[:select]) && !sel.empty? 29: select(*(columns.zip(sel).reject{|c, s| cols.include?(c)}.map{|c, s| s} - cols)) 30: else 31: select(*(columns - cols)) 32: end 33: end
Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.
DB[:items].all # Uses the :read_only or :default server DB[:items].delete # Uses the :default server DB[:items].server(:blah).delete # Uses the :blah server
# File lib/sequel/dataset/query.rb, line 793 793: def server(servr) 794: clone(:server=>servr) 795: end
Alias for update, but not aliased directly so subclasses don’t have to override both methods.
# File lib/sequel/dataset/actions.rb, line 507 507: def set(*args) 508: update(*args) 509: end
Set the default values for insert and update statements. The values hash passed to insert or update are merged into this hash, so any values in the hash passed to insert or update will override values passed to this method.
DB[:items].set_defaults(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b') # INSERT INTO items (a, c, b) VALUES ('d', 'c', 'b')
# File lib/sequel/dataset/query.rb, line 803 803: def set_defaults(hash) 804: clone(:defaults=>(@opts[:defaults]||{}).merge(hash)) 805: end
This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.
graph_aliases | Should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name. |
DB[:artists].graph(:albums, :artist_id=>:id). set_graph_aliases(:name=>:artists, :album_name=>[:albums, :name], :forty_two=>[:albums, :fourtwo, 42]).first # SELECT artists.name, albums.name AS album_name, 42 AS forty_two ... # => {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}
# File lib/sequel/dataset/graph.rb, line 230 230: def set_graph_aliases(graph_aliases) 231: columns, graph_aliases = graph_alias_columns(graph_aliases) 232: ds = select(*columns) 233: ds.opts[:graph_aliases] = graph_aliases 234: ds 235: end
Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update, so values will override any values given in the insert/update hashes.
DB[:items].set_overrides(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b') # INSERT INTO items (a, c, b) VALUES ('a', 'c', 'b')
# File lib/sequel/dataset/query.rb, line 813 813: def set_overrides(hash) 814: clone(:overrides=>hash.merge(@opts[:overrides]||{})) 815: end
Returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method.
# File lib/sequel/dataset/actions.rb, line 514 514: def single_record 515: clone(:limit=>1).each{|r| return r} 516: nil 517: end
Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method.
# File lib/sequel/dataset/actions.rb, line 522 522: def single_value 523: if r = naked.ungraphed.single_record 524: r.values.first 525: end 526: end
Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.
# File lib/sequel/dataset/misc.rb, line 154 154: def split_alias(c) 155: case c 156: when Symbol 157: c_table, column, aliaz = split_symbol(c) 158: [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz] 159: when SQL::AliasedExpression 160: [c.expression, c.aliaz] 161: when SQL::JoinClause 162: [c.table, c.table_alias] 163: else 164: [c, nil] 165: end 166: end
Makes each yield arrays of rows, with each array containing the rows for a given result set. Does not work with graphing. So you can submit SQL with multiple statements and easily determine which statement returned which results.
Modifies the row_proc of the returned dataset so that it still works as expected (running on the hashes instead of on the arrays of hashes). If you modify the row_proc afterward, note that it will receive an array of hashes instead of a hash.
# File lib/sequel/adapters/mysql.rb, line 333 333: def split_multiple_result_sets 334: raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph] 335: ds = clone(:split_multiple_result_sets=>true) 336: ds.row_proc = proc{|x| x.map{|h| row_proc.call(h)}} if row_proc 337: ds 338: end
Same as select_sql, not aliased directly to make subclassing simpler.
# File lib/sequel/dataset/sql.rb, line 144 144: def sql 145: select_sql 146: end
Returns the sum for the given column.
DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1 # => 55
# File lib/sequel/dataset/actions.rb, line 532 532: def sum(column) 533: aggregate_dataset.get{sum(column)} 534: end
Whether the dataset supports common table expressions (the WITH clause). If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.
# File lib/sequel/dataset/features.rb, line 48 48: def supports_cte?(type=:select) 49: send(:"#{type}_clause_methods").include?(:"#{type}_with_sql") 50: end
Whether the dataset supports common table expressions (the WITH clause) in subqueries. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.
# File lib/sequel/dataset/features.rb, line 55 55: def supports_cte_in_subqueries? 56: false 57: end
Whether the dataset supports CUBE with GROUP BY.
# File lib/sequel/dataset/features.rb, line 65 65: def supports_group_cube? 66: false 67: end
Whether the dataset supports ROLLUP with GROUP BY.
# File lib/sequel/dataset/features.rb, line 70 70: def supports_group_rollup? 71: false 72: end
Whether this dataset supports the insert_select method for returning all columns values directly from an insert query.
# File lib/sequel/dataset/features.rb, line 76 76: def supports_insert_select? 77: supports_returning?(:insert) 78: end
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
# File lib/sequel/dataset/features.rb, line 81 81: def supports_intersect_except? 82: true 83: end
Whether the dataset supports the IS TRUE syntax.
# File lib/sequel/dataset/features.rb, line 91 91: def supports_is_true? 92: true 93: end
Whether the dataset supports the JOIN table USING (column1, …) syntax.
# File lib/sequel/dataset/features.rb, line 96 96: def supports_join_using? 97: true 98: end
Whether modifying joined datasets is supported.
# File lib/sequel/dataset/features.rb, line 101 101: def supports_modifying_joins? 102: false 103: end
Whether the IN/NOT IN operators support multiple columns when an array of values is given.
# File lib/sequel/dataset/features.rb, line 107 107: def supports_multiple_column_in? 108: true 109: end
Whether the RETURNING clause is supported for the given type of query. type can be :insert, :update, or :delete.
# File lib/sequel/dataset/features.rb, line 119 119: def supports_returning?(type) 120: send(:"#{type}_clause_methods").include?(:"#{type}_returning_sql") 121: end
Whether the dataset supports timezones in literal timestamps
# File lib/sequel/dataset/features.rb, line 129 129: def supports_timestamp_timezones? 130: false 131: end
Whether the dataset supports fractional seconds in literal timestamps
# File lib/sequel/dataset/features.rb, line 134 134: def supports_timestamp_usecs? 135: true 136: end
Whether the dataset supports window functions.
# File lib/sequel/dataset/features.rb, line 139 139: def supports_window_functions? 140: false 141: end
Returns a string in CSV format containing the dataset records. By default the CSV representation includes the column titles in the first line. You can turn that off by passing false as the include_column_titles argument.
This does not use a CSV library or handle quoting of values in any way. If any values in any of the rows could include commas or line endings, you shouldn’t use this.
puts DB[:table].to_csv # SELECT * FROM table # id,name # 1,Jim # 2,Bob
# File lib/sequel/dataset/actions.rb, line 549 549: def to_csv(include_column_titles = true) 550: n = naked 551: cols = n.columns 552: csv = '' 553: csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles 554: n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"} 555: csv 556: end
Return a string that can be processed by the dot program (included with graphviz) in order to see a visualization of the dataset’s abstract syntax tree.
# File lib/sequel/extensions/to_dot.rb, line 145 145: def to_dot 146: ToDot.output(self) 147: end
Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].to_hash(:id, :name) # SELECT * FROM table # {1=>'Jim', 2=>'Bob', ...} DB[:table].to_hash(:id) # SELECT * FROM table # {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].to_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table # {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...} DB[:table].to_hash([:id, :name]) # SELECT * FROM table # {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob'=>{:id=>2, :name=>'Bob'}, ...}
# File lib/sequel/dataset/actions.rb, line 577 577: def to_hash(key_column, value_column = nil) 578: h = {} 579: if value_column 580: return naked.to_hash(key_column, value_column) if row_proc 581: if value_column.is_a?(Array) 582: if key_column.is_a?(Array) 583: each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)} 584: else 585: each{|r| h[r[key_column]] = r.values_at(*value_column)} 586: end 587: else 588: if key_column.is_a?(Array) 589: each{|r| h[r.values_at(*key_column)] = r[value_column]} 590: else 591: each{|r| h[r[key_column]] = r[value_column]} 592: end 593: end 594: elsif key_column.is_a?(Array) 595: each{|r| h[r.values_at(*key_column)] = r} 596: else 597: each{|r| h[r[key_column]] = r} 598: end 599: h 600: end
Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].to_hash(:name, :id) # SELECT * FROM table # {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...} DB[:table].to_hash(:name) # SELECT * FROM table # {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].to_hash([:first, :middle], [:last, :id]) # SELECT * FROM table # {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...} DB[:table].to_hash([:first, :middle]) # SELECT * FROM table # {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}
# File lib/sequel/dataset/actions.rb, line 620 620: def to_hash_groups(key_column, value_column = nil) 621: h = {} 622: if value_column 623: return naked.to_hash_groups(key_column, value_column) if row_proc 624: if value_column.is_a?(Array) 625: if key_column.is_a?(Array) 626: each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)} 627: else 628: each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)} 629: end 630: else 631: if key_column.is_a?(Array) 632: each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]} 633: else 634: each{|r| (h[r[key_column]] ||= []) << r[value_column]} 635: end 636: end 637: elsif key_column.is_a?(Array) 638: each{|r| (h[r.values_at(*key_column)] ||= []) << r} 639: else 640: each{|r| (h[r[key_column]] ||= []) << r} 641: end 642: h 643: end
Truncates the dataset. Returns nil.
DB[:table].truncate # TRUNCATE table # => nil
# File lib/sequel/dataset/actions.rb, line 649 649: def truncate 650: execute_ddl(truncate_sql) 651: end
Returns a TRUNCATE SQL query string. See truncate
DB[:items].truncate_sql # => 'TRUNCATE items'
# File lib/sequel/dataset/sql.rb, line 151 151: def truncate_sql 152: if opts[:sql] 153: static_sql(opts[:sql]) 154: else 155: check_truncation_allowed! 156: raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having] 157: _truncate_sql(source_list(opts[:from])) 158: end 159: end
Unbind bound variables from this dataset’s filter and return an array of two objects. The first object is a modified dataset where the filter has been replaced with one that uses bound variable placeholders. The second object is the hash of unbound variables. You can then prepare and execute (or just call) the dataset with the bound variables to get results.
ds, bv = DB[:items].filter(:a=>1).unbind ds # SELECT * FROM items WHERE (a = $a) bv # {:a => 1} ds.call(:select, bv)
# File lib/sequel/dataset/query.rb, line 827 827: def unbind 828: u = Unbinder.new 829: ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join])) 830: [ds, u.binds] 831: end
Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).
# File lib/sequel/dataset/graph.rb, line 239 239: def ungraphed 240: clone(:graph=>nil, :graph_aliases=>nil) 241: end
Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.
DB[:items].group(:a).having(:a=>1).where(:b).ungrouped # SELECT * FROM items WHERE b
# File lib/sequel/dataset/query.rb, line 845 845: def ungrouped 846: clone(:group => nil, :having => nil) 847: end
Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:
:alias | Use the given value as the from_self alias |
:all | Set to true to use UNION ALL instead of UNION, so duplicate rows can occur |
:from_self | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].union(DB[:other_items]) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1 DB[:items].union(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items UNION ALL SELECT * FROM other_items DB[:items].union(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 865 865: def union(dataset, opts={}) 866: opts = {:all=>opts} unless opts.is_a?(Hash) 867: compound_clone(:union, dataset, opts) 868: end
Returns a copy of the dataset with no limit or offset.
DB[:items].limit(10, 20).unlimited # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 873 873: def unlimited 874: clone(:limit=>nil, :offset=>nil) 875: end
Returns a copy of the dataset with no order.
DB[:items].order(:a).unordered # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 880 880: def unordered 881: order(nil) 882: end
Creates a unique table alias that hasn’t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.
You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.
DB[:table].unused_table_alias(:t) # => :t DB[:table].unused_table_alias(:table) # => :table_0 DB[:table, :table_0].unused_table_alias(:table) # => :table_1 DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2]) # => :table_3
# File lib/sequel/dataset/misc.rb, line 190 190: def unused_table_alias(table_alias, used_aliases = []) 191: table_alias = alias_symbol(table_alias) 192: used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from] 193: used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join] 194: if used_aliases.include?(table_alias) 195: i = 0 196: loop do 197: ta = :"#{table_alias}_#{i}" 198: return ta unless used_aliases.include?(ta) 199: i += 1 200: end 201: else 202: table_alias 203: end 204: end
Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. values should a hash where the keys are columns to set and values are the values to which to set the columns.
DB[:table].update(:x=>nil) # UPDATE table SET x = NULL # => 10 DB[:table].update(:x=>:x+1, :y=>0) # UPDATE table SET x = (x + 1), y = 0 # => 10
# File lib/sequel/dataset/actions.rb, line 663 663: def update(values={}, &block) 664: sql = update_sql(values) 665: if uses_returning?(:update) 666: returning_fetch_rows(sql, &block) 667: else 668: execute_dui(sql) 669: end 670: end
Formats an UPDATE statement using the given values. See update.
DB[:items].update_sql(:price => 100, :category => 'software') # => "UPDATE items SET price = 100, category = 'software'
Raises an Error if the dataset is grouped or includes more than one table.
# File lib/sequel/dataset/sql.rb, line 168 168: def update_sql(values = {}) 169: return static_sql(opts[:sql]) if opts[:sql] 170: check_modification_allowed! 171: clone(:values=>values)._update_sql 172: end
Uses a cursor for fetching records, instead of fetching the entire result set at once. Can be used to process large datasets without holding all rows in memory (which is what the underlying drivers do by default). Options:
:rows_per_fetch - the number of rows per fetch (default 1000). Higher numbers result in fewer queries but greater memory use.
Usage:
DB[:huge_table].use_cursor.each{|row| p row} DB[:huge_table].use_cursor(:rows_per_fetch=>10000).each{|row| p row}
This is untested with the prepared statement/bound variable support, and unlikely to work with either.
# File lib/sequel/adapters/postgres.rb, line 584 584: def use_cursor(opts={}) 585: clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts)) 586: end
Add a condition to the WHERE clause. See filter for argument types.
DB[:items].group(:a).having(:a).filter(:b) # SELECT * FROM items GROUP BY a HAVING a AND b DB[:items].group(:a).having(:a).where(:b) # SELECT * FROM items WHERE b GROUP BY a HAVING a
# File lib/sequel/dataset/query.rb, line 891 891: def where(*cond, &block) 892: _filter(:where, *cond, &block) 893: end
The SQL fragment for the given window function’s function and window.
# File lib/sequel/dataset/sql.rb, line 695 695: def window_function_sql_append(sql, function, window) 696: literal_append(sql, function) 697: sql << OVER 698: literal_append(sql, window) 699: end
The SQL fragment for the given window’s options.
# File lib/sequel/dataset/sql.rb, line 654 654: def window_sql_append(sql, opts) 655: raise(Error, 'This dataset does not support window functions') unless supports_window_functions? 656: sql << PAREN_OPEN 657: window, part, order, frame = opts.values_at(:window, :partition, :order, :frame) 658: space = false 659: space_s = SPACE 660: if window 661: literal_append(sql, window) 662: space = true 663: end 664: if part 665: sql << space_s if space 666: sql << PARTITION_BY 667: expression_list_append(sql, Array(part)) 668: space = true 669: end 670: if order 671: sql << space_s if space 672: sql << ORDER_BY_NS 673: expression_list_append(sql, Array(order)) 674: space = true 675: end 676: case frame 677: when nil 678: # nothing 679: when :all 680: sql << space_s if space 681: sql << FRAME_ALL 682: when :rows 683: sql << space_s if space 684: sql << FRAME_ROWS 685: when String 686: sql << space_s if space 687: sql << frame 688: else 689: raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil" 690: end 691: sql << PAREN_CLOSE 692: end
Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query. Options:
:args | Specify the arguments/columns for the CTE, should be an array of symbols. |
:recursive | Specify that this is a recursive CTE |
DB[:items].with(:items, DB[:syx].filter(:name.like('A%'))) # WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 903 903: def with(name, dataset, opts={}) 904: raise(Error, 'This datatset does not support common table expressions') unless supports_cte? 905: if hoist_cte?(dataset) 906: s, ds = hoist_cte(dataset) 907: s.with(name, ds, opts) 908: else 909: clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)]) 910: end 911: end
Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE. Options:
:args | Specify the arguments/columns for the CTE, should be an array of symbols. |
:union_all | Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts. |
DB[:t].select(:i___id, :pi___parent_id). with_recursive(:t, DB[:i1].filter(:parent_id=>nil), DB[:t].join(:t, :i=>:parent_id).select(:i1__id, :i1__parent_id), :args=>[:i, :pi]) # WITH RECURSIVE t(i, pi) AS ( # SELECT * FROM i1 WHERE (parent_id IS NULL) # UNION ALL # SELECT i1.id, i1.parent_id FROM t INNER JOIN t ON (t.i = t.parent_id) # ) # SELECT i AS id, pi AS parent_id FROM t
# File lib/sequel/dataset/query.rb, line 930 930: def with_recursive(name, nonrecursive, recursive, opts={}) 931: raise(Error, 'This datatset does not support common table expressions') unless supports_cte? 932: if hoist_cte?(nonrecursive) 933: s, ds = hoist_cte(nonrecursive) 934: s.with_recursive(name, ds, recursive, opts) 935: elsif hoist_cte?(recursive) 936: s, ds = hoist_cte(recursive) 937: s.with_recursive(name, nonrecursive, ds, opts) 938: else 939: clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]) 940: end 941: end
Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.
DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo
You can use placeholders in your SQL and provide arguments for those placeholders:
DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo
You can also provide a method name and arguments to call to get the SQL:
DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)
# File lib/sequel/dataset/query.rb, line 955 955: def with_sql(sql, *args) 956: if sql.is_a?(Symbol) 957: sql = send(sql, *args) 958: else 959: sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty? 960: end 961: clone(:sql=>sql) 962: end
Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It’s significantly faster as it does not require cloning the current dataset.
# File lib/sequel/dataset/actions.rb, line 675 675: def with_sql_delete(sql) 676: execute_dui(sql) 677: end
Internals of #. If primary key values are requested, use separate insert commands for each row. Otherwise, call # and execute each statement it gives separately.
# File lib/sequel/dataset/actions.rb, line 684 684: def _import(columns, values, opts) 685: trans_opts = opts.merge(:server=>@opts[:server]) 686: if opts[:return] == :primary_key 687: @db.transaction(trans_opts){values.map{|v| insert(columns, v)}} 688: else 689: stmts = multi_insert_sql(columns, values) 690: @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}} 691: end 692: end
Formats in INSERT statement using the stored columns and values.
# File lib/sequel/dataset/sql.rb, line 704 704: def _insert_sql 705: clause_sql(:insert) 706: end
Return an array of arrays of values given by the symbols in ret_cols.
# File lib/sequel/dataset/actions.rb, line 695 695: def _select_map_multiple(ret_cols) 696: map{|r| r.values_at(*ret_cols)} 697: end
Returns an array of the first value in each row.
# File lib/sequel/dataset/actions.rb, line 700 700: def _select_map_single 701: map{|r| r.values.first} 702: end
Formats an UPDATE statement using the stored values.
# File lib/sequel/dataset/sql.rb, line 709 709: def _update_sql 710: clause_sql(:update) 711: end
Add the dataset to the list of compounds
# File lib/sequel/dataset/query.rb, line 967 967: def compound_clone(type, dataset, opts) 968: if hoist_cte?(dataset) 969: s, ds = hoist_cte(dataset) 970: return s.compound_clone(type, ds, opts) 971: end 972: ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]]) 973: opts[:from_self] == false ? ds : ds.from_self(opts) 974: end
Return a from_self dataset if an order or limit is specified, so it works as expected with UNION, EXCEPT, and INTERSECT clauses.
# File lib/sequel/dataset/sql.rb, line 715 715: def compound_from_self 716: (@opts[:limit] || @opts[:order]) ? from_self : self 717: end
Return true if the dataset has a non-nil value for any key in opts.
# File lib/sequel/dataset/query.rb, line 977 977: def options_overlap(opts) 978: !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty? 979: end
Whether this dataset is a simple SELECT * FROM table.
# File lib/sequel/dataset/query.rb, line 982 982: def simple_select_all? 983: o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)} 984: o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression)) 985: end
Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.
# File lib/sequel/dataset/prepared_statements.rb, line 260 260: def to_prepared_statement(type, values=nil) 261: ps = bind 262: ps.extend(PreparedStatementMethods) 263: ps.orig_dataset = self 264: ps.prepared_type = type 265: ps.prepared_modify_values = values 266: ps 267: end
Internal filter method so it works on either the having or where clauses.
# File lib/sequel/dataset/query.rb, line 1003 1003: def _filter(clause, *cond, &block) 1004: _filter_or_exclude(false, clause, *cond, &block) 1005: end
Internal filter/exclude method so it works on either the having or where clauses.
# File lib/sequel/dataset/query.rb, line 990 990: def _filter_or_exclude(invert, clause, *cond, &block) 991: cond = cond.first if cond.size == 1 992: if cond.respond_to?(:empty?) && cond.empty? && !block 993: clone 994: else 995: cond = filter_expr(cond, &block) 996: cond = SQL::BooleanExpression.invert(cond) if invert 997: cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause] 998: clone(clause => cond) 999: end 1000: end
Internals of select_hash and select_hash_groups
# File lib/sequel/dataset/actions.rb, line 707 707: def _select_hash(meth, key_column, value_column) 708: if key_column.is_a?(Array) 709: if value_column.is_a?(Array) 710: select(*(key_column + value_column)).send(meth, key_column.map{|c| hash_key_symbol(c)}, value_column.map{|c| hash_key_symbol(c)}) 711: else 712: select(*(key_column + [value_column])).send(meth, key_column.map{|c| hash_key_symbol(c)}, hash_key_symbol(value_column)) 713: end 714: elsif value_column.is_a?(Array) 715: select(key_column, *value_column).send(meth, hash_key_symbol(key_column), value_column.map{|c| hash_key_symbol(c)}) 716: else 717: select(key_column, value_column).send(meth, hash_key_symbol(key_column), hash_key_symbol(value_column)) 718: end 719: end
Internals of select_map and select_order_map
# File lib/sequel/dataset/actions.rb, line 722 722: def _select_map(column, order, &block) 723: ds = naked.ungraphed 724: columns = Array(column) 725: virtual_row_columns(columns, block) 726: select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns 727: ds = ds.select(*select_cols) 728: ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order 729: if column.is_a?(Array) || (columns.length > 1) 730: ds._select_map_multiple(select_cols.map{|c| hash_key_symbol(c)}) 731: else 732: ds._select_map_single 733: end 734: end
Formats the truncate statement. Assumes the table given has already been literalized.
# File lib/sequel/dataset/sql.rb, line 723 723: def _truncate_sql(table) 724: "TRUNCATE TABLE #{table}" 725: end
Clone of this dataset usable in aggregate operations. Does a from_self if dataset contains any parameters that would affect normal aggregation, or just removes an existing order if not.
# File lib/sequel/dataset/sql.rb, line 766 766: def aggregate_dataset 767: options_overlap(COUNT_FROM_SELF_OPTS) ? from_self : unordered 768: end
Returns an appropriate symbol for the alias represented by s.
# File lib/sequel/dataset/sql.rb, line 728 728: def alias_alias_symbol(s) 729: case s 730: when Symbol 731: s 732: when String 733: s.to_sym 734: when SQL::Identifier 735: s.value.to_s.to_sym 736: else 737: raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}" 738: end 739: end
Returns an appropriate alias symbol for the given object, which can be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.
# File lib/sequel/dataset/sql.rb, line 744 744: def alias_symbol(sym) 745: case sym 746: when Symbol 747: s, t, a = split_symbol(sym) 748: a || s ? (a || t).to_sym : sym 749: when String 750: sym.to_sym 751: when SQL::Identifier 752: sym.value.to_s.to_sym 753: when SQL::QualifiedIdentifier 754: alias_symbol(sym.column) 755: when SQL::AliasedExpression 756: alias_alias_symbol(sym.aliaz) 757: else 758: raise Error, "Invalid alias for alias_symbol: #{sym.inspect}" 759: end 760: end
# File lib/sequel/dataset/sql.rb, line 770 770: def argument_list_append(sql, args) 771: c = false 772: comma = COMMA 773: args.each do |a| 774: sql << comma if c 775: sql << a.to_s 776: c ||= true 777: end 778: end
SQL fragment for specifying an alias. expression should already be literalized.
# File lib/sequel/dataset/sql.rb, line 781 781: def as_sql_append(sql, aliaz) 782: sql << AS 783: quote_identifier_append(sql, aliaz) 784: end
Raise an InvalidOperation exception if deletion is not allowed for this dataset
# File lib/sequel/dataset/sql.rb, line 788 788: def check_modification_allowed! 789: raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group] 790: raise(InvalidOperation, "Joined datasets cannot be modified") if !supports_modifying_joins? && joined_dataset? 791: end
Alias of check_modification_allowed!
# File lib/sequel/dataset/sql.rb, line 794 794: def check_truncation_allowed! 795: check_modification_allowed! 796: end
Prepare an SQL statement by calling all clause methods for the given statement type.
# File lib/sequel/dataset/sql.rb, line 799 799: def clause_sql(type) 800: sql = @opts[:append_sql] || sql_string_origin 801: send("#{type}_clause_methods").each{|x| send(x, sql)} 802: sql 803: end
Converts an array of column names into a comma seperated string of column names. If the array is empty, a wildcard (*) is returned.
# File lib/sequel/dataset/sql.rb, line 807 807: def column_list_append(sql, columns) 808: if (columns.nil? || columns.empty?) 809: sql << WILDCARD 810: else 811: expression_list_append(sql, columns) 812: end 813: end
Yield each two pair of arguments to the block, which should return a string representing the SQL code for those two arguments. If more than 2 arguments are provided, all calls to the block # after the first will have a LiteralString as the first argument, representing the application of the block to the previous arguments.
# File lib/sequel/dataset/sql.rb, line 821 821: def complex_expression_arg_pairs(args) 822: case args.length 823: when 1 824: literal(args.at(0)) 825: when 2 826: yield args.at(0), args.at(1) 827: else 828: args.inject{|m, a| LiteralString.new(yield(m, a))} 829: end 830: end
The SQL to use for the dataset used in a UNION/INTERSECT/EXCEPT clause.
# File lib/sequel/dataset/sql.rb, line 833 833: def compound_dataset_sql_append(sql, ds) 834: subselect_sql_append(sql, ds) 835: end
Use a cursor to fetch groups of records at a time, yielding them to the block.
# File lib/sequel/adapters/postgres.rb, line 703 703: def cursor_fetch_rows(sql) 704: server_opts = {:server=>@opts[:server] || :read_only} 705: db.transaction(server_opts) do 706: begin 707: execute_ddl("DECLARE sequel_cursor NO SCROLL CURSOR WITHOUT HOLD FOR #{sql}", server_opts) 708: rows_per_fetch = @opts[:cursor][:rows_per_fetch].to_i 709: rows_per_fetch = 1000 if rows_per_fetch <= 0 710: fetch_sql = "FETCH FORWARD #{rows_per_fetch} FROM sequel_cursor" 711: cols = nil 712: # Load columns only in the first fetch, so subsequent fetches are faster 713: execute(fetch_sql) do |res| 714: cols = fetch_rows_set_cols(res) 715: yield_hash_rows(res, cols){|h| yield h} 716: return if res.ntuples < rows_per_fetch 717: end 718: loop do 719: execute(fetch_sql) do |res| 720: yield_hash_rows(res, cols){|h| yield h} 721: return if res.ntuples < rows_per_fetch 722: end 723: end 724: ensure 725: execute_ddl("CLOSE sequel_cursor", server_opts) 726: end 727: end 728: end
The alias to use for datasets, takes a number to make sure the name is unique.
# File lib/sequel/dataset/sql.rb, line 838 838: def dataset_alias(number) 839: :"#{DATASET_ALIAS_BASE_NAME}#{number}" 840: end
Return self if the dataset already has a server, or a cloned dataset with the default server otherwise.
# File lib/sequel/dataset/query.rb, line 1079 1079: def default_server 1080: @opts[:server] ? self : clone(:server=>:default) 1081: end
Set the server to use to :default unless it is already set in the passed opts
# File lib/sequel/dataset/actions.rb, line 737 737: def default_server_opts(opts) 738: {:server=>@opts[:server] || :default}.merge(opts) 739: end
The strftime format to use when literalizing the time.
# File lib/sequel/dataset/sql.rb, line 843 843: def default_timestamp_format 844: requires_sql_standard_datetimes? ? STANDARD_TIMESTAMP_FORMAT : TIMESTAMP_FORMAT 845: end
# File lib/sequel/dataset/sql.rb, line 852 852: def delete_delete_sql(sql) 853: sql << DELETE 854: end
# File lib/sequel/dataset/sql.rb, line 868 868: def empty_array_value(op, cols) 869: if Sequel.empty_array_handle_nulls 870: c = Array(cols) 871: SQL::BooleanExpression.from_value_pairs(c.zip(c), :AND, op == :IN) 872: else 873: {1 => ((op == :IN) ? 0 : 1)} 874: end 875: end
Execute the given select SQL on the database using execute. Use the :read_only server unless a specific server is set.
# File lib/sequel/dataset/actions.rb, line 743 743: def execute(sql, opts={}, &block) 744: @db.execute(sql, {:server=>@opts[:server] || :read_only}.merge(opts), &block) 745: end
Set the :type option to :select if it hasn’t been set.
# File lib/sequel/adapters/mysql.rb, line 343 343: def execute(sql, opts={}, &block) 344: super(sql, {:type=>:select}.merge(opts), &block) 345: end
Execute the given SQL on the database using execute_ddl.
# File lib/sequel/dataset/actions.rb, line 748 748: def execute_ddl(sql, opts={}, &block) 749: @db.execute_ddl(sql, default_server_opts(opts), &block) 750: nil 751: end
Execute the given SQL on the database using execute_dui.
# File lib/sequel/dataset/actions.rb, line 754 754: def execute_dui(sql, opts={}, &block) 755: @db.execute_dui(sql, default_server_opts(opts), &block) 756: end
Execute the given SQL on the database using execute_insert.
# File lib/sequel/dataset/actions.rb, line 759 759: def execute_insert(sql, opts={}, &block) 760: @db.execute_insert(sql, default_server_opts(opts), &block) 761: end
Converts an array of expressions into a comma separated string of expressions.
# File lib/sequel/dataset/sql.rb, line 858 858: def expression_list_append(sql, columns) 859: c = false 860: co = COMMA 861: columns.each do |col| 862: sql << co if c 863: literal_append(sql, col) 864: c ||= true 865: end 866: end
Set the @columns based on the result set, and return the array of field numers, type conversion procs, and name symbol arrays.
# File lib/sequel/adapters/postgres.rb, line 732 732: def fetch_rows_set_cols(res) 733: cols = [] 734: procs = db.conversion_procs 735: res.nfields.times do |fieldnum| 736: cols << [fieldnum, procs[res.ftype(fieldnum)], output_identifier(res.fname(fieldnum))] 737: end 738: @columns = cols.map{|c| c.at(2)} 739: cols 740: end
SQL expression object based on the expr type. See filter.
# File lib/sequel/dataset/query.rb, line 1008 1008: def filter_expr(expr = nil, &block) 1009: expr = nil if expr == [] 1010: if expr && block 1011: return SQL::BooleanExpression.new(:AND, filter_expr(expr), filter_expr(block)) 1012: elsif block 1013: expr = block 1014: end 1015: case expr 1016: when Hash 1017: SQL::BooleanExpression.from_value_pairs(expr) 1018: when Array 1019: if (sexpr = expr.at(0)).is_a?(String) 1020: SQL::PlaceholderLiteralString.new(sexpr, expr[1..1], true) 1021: elsif Sequel.condition_specifier?(expr) 1022: SQL::BooleanExpression.from_value_pairs(expr) 1023: else 1024: SQL::BooleanExpression.new(:AND, *expr.map{|x| filter_expr(x)}) 1025: end 1026: when Proc 1027: filter_expr(Sequel.virtual_row(&expr)) 1028: when SQL::NumericExpression, SQL::StringExpression 1029: raise(Error, "Invalid SQL Expression type: #{expr.inspect}") 1030: when Symbol, SQL::Expression 1031: expr 1032: when TrueClass, FalseClass 1033: if supports_where_true? 1034: SQL::BooleanExpression.new(:NOOP, expr) 1035: elsif expr 1036: SQL::Constants::SQLTRUE 1037: else 1038: SQL::Constants::SQLFALSE 1039: end 1040: when String 1041: LiteralString.new("(#{expr})") 1042: else 1043: raise(Error, 'Invalid filter argument') 1044: end 1045: end
Format the timestamp based on the default_timestamp_format, with a couple of modifiers. First, allow %N to be used for fractions seconds (if the database supports them), and override %z to always use a numeric offset of hours and minutes.
# File lib/sequel/dataset/sql.rb, line 881 881: def format_timestamp(v) 882: v2 = db.from_application_timestamp(v) 883: fmt = default_timestamp_format.gsub(FORMAT_TIMESTAMP_RE) do |m| 884: if m == FORMAT_USEC 885: format_timestamp_usec(v.is_a?(DateTime) ? v.sec_fraction*(RUBY_VERSION < V190 ? 86400000000 : 1000000) : v.usec) if supports_timestamp_usecs? 886: else 887: if supports_timestamp_timezones? 888: # Would like to just use %z format, but it doesn't appear to work on Windows 889: # Instead, the offset fragment is constructed manually 890: minutes = (v2.is_a?(DateTime) ? v2.offset * 1440 : v2.utc_offset/60).to_i 891: format_timestamp_offset(*minutes.divmod(60)) 892: end 893: end 894: end 895: v2.strftime(fmt) 896: end
Return the SQL timestamp fragment to use for the timezone offset.
# File lib/sequel/dataset/sql.rb, line 899 899: def format_timestamp_offset(hour, minute) 900: sprintf(FORMAT_OFFSET, hour, minute) 901: end
Return the SQL timestamp fragment to use for the fractional time part. Should start with the decimal point. Uses 6 decimal places by default.
# File lib/sequel/dataset/sql.rb, line 905 905: def format_timestamp_usec(usec) 906: sprintf(FORMAT_TIMESTAMP_USEC, usec) 907: end
Transform the hash of graph aliases and return a two element array where the first element is an array of identifiers suitable to pass to a select method, and the second is a new hash of preprocessed graph aliases.
# File lib/sequel/dataset/graph.rb, line 248 248: def graph_alias_columns(graph_aliases) 249: gas = {} 250: identifiers = graph_aliases.collect do |col_alias, tc| 251: table, column, value = Array(tc) 252: column ||= col_alias 253: gas[col_alias] = [table, column] 254: identifier = value || SQL::QualifiedIdentifier.new(table, column) 255: identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias 256: identifier 257: end 258: [identifiers, gas] 259: end
Fetch the rows, split them into component table parts, tranform and run the row_proc on each part (if applicable), and yield a hash of the parts.
# File lib/sequel/dataset/graph.rb, line 264 264: def graph_each 265: # Reject tables with nil datasets, as they are excluded from 266: # the result set 267: datasets = @opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 268: # Get just the list of table aliases into a local variable, for speed 269: table_aliases = datasets.collect{|ta,ds| ta} 270: # Get an array of arrays, one for each dataset, with 271: # the necessary information about each dataset, for speed 272: datasets = datasets.collect{|ta, ds| [ta, ds, ds.row_proc]} 273: # Use the manually set graph aliases, if any, otherwise 274: # use the ones automatically created by .graph 275: column_aliases = @opts[:graph_aliases] || @opts[:graph][:column_aliases] 276: fetch_rows(select_sql) do |r| 277: graph = {} 278: # Create the sub hashes, one per table 279: table_aliases.each{|ta| graph[ta]={}} 280: # Split the result set based on the column aliases 281: # If there are columns in the result set that are 282: # not in column_aliases, they are ignored 283: column_aliases.each do |col_alias, tc| 284: ta, column = tc 285: graph[ta][column] = r[col_alias] 286: end 287: # For each dataset run the row_proc if applicable 288: datasets.each do |ta,ds,rp| 289: g = graph[ta] 290: graph[ta] = if g.values.any?{|x| !x.nil?} 291: rp ? rp.call(g) : g 292: else 293: nil 294: end 295: end 296: 297: yield graph 298: end 299: self 300: end
Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned.
# File lib/sequel/dataset/actions.rb, line 766 766: def hash_key_symbol(s) 767: case s 768: when Symbol 769: _, c, a = split_symbol(s) 770: (a || c).to_sym 771: when SQL::Identifier 772: hash_key_symbol(s.value) 773: when SQL::QualifiedIdentifier 774: hash_key_symbol(s.column) 775: when SQL::AliasedExpression 776: hash_key_symbol(s.aliaz) 777: when String 778: s.to_sym 779: else 780: raise(Error, "#{s.inspect} is not supported, should be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression") 781: end 782: end
Return two datasets, the first a clone of the receiver with the WITH clause from the given dataset added to it, and the second a clone of the given dataset with the WITH clause removed.
# File lib/sequel/dataset/query.rb, line 1050 1050: def hoist_cte(ds) 1051: [clone(:with => (opts[:with] || []) + ds.opts[:with]), ds.clone(:with => nil)] 1052: end
Whether CTEs need to be hoisted from the given ds into the current ds.
# File lib/sequel/dataset/query.rb, line 1055 1055: def hoist_cte?(ds) 1056: ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries? 1057: end
Append the value, but special case regular (non-literal, non-blob) strings so that they are considered as identifiers and not SQL strings.
# File lib/sequel/dataset/sql.rb, line 911 911: def identifier_append(sql, v) 912: if v.is_a?(String) 913: case v 914: when LiteralString 915: sql << v 916: when SQL::Blob 917: literal_append(sql, v) 918: else 919: quote_identifier_append(sql, v) 920: end 921: else 922: literal_append(sql, v) 923: end 924: end
Modify the identifier returned from the database based on the identifier_output_method.
# File lib/sequel/dataset/sql.rb, line 929 929: def input_identifier(v) 930: (i = identifier_input_method) ? v.to_s.send(i) : v.to_s 931: end
SQL fragment specifying the columns to insert into
# File lib/sequel/dataset/sql.rb, line 945 945: def insert_columns_sql(sql) 946: columns = opts[:columns] 947: if columns && !columns.empty? 948: sql << PAREN_SPACE_OPEN 949: c = false 950: co = COMMA 951: columns.each do |col| 952: sql << co if c 953: identifier_append(sql, col) 954: c ||= true 955: end 956: sql << PAREN_CLOSE 957: end 958: end
# File lib/sequel/dataset/sql.rb, line 960 960: def insert_insert_sql(sql) 961: sql << INSERT 962: end
SQL fragment specifying the values to return.
# File lib/sequel/dataset/sql.rb, line 985 985: def insert_returning_sql(sql) 986: if opts.has_key?(:returning) 987: sql << RETURNING 988: column_list_append(sql, Array(opts[:returning])) 989: end 990: end
Whether insert(nil) or insert({}) must be emulated by using at least one value, false by default.
# File lib/sequel/dataset/features.rb, line 153 153: def insert_supports_empty_values? 154: true 155: end
SQL fragment specifying the values to insert.
# File lib/sequel/dataset/sql.rb, line 965 965: def insert_values_sql(sql) 966: case values = opts[:values] 967: when Array 968: if values.empty? 969: sql << DEFAULT_VALUES 970: else 971: sql << VALUES 972: literal_append(sql, values) 973: end 974: when Dataset 975: sql << SPACE 976: subselect_sql_append(sql, values) 977: when LiteralString 978: sql << SPACE << values 979: else 980: raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}" 981: end 982: end
Inverts the given order by breaking it into a list of column references and inverting them.
DB[:items].invert_order([:id.desc]]) #=> [:id] DB[:items].invert_order(:category, :price.desc]) #=> [:category.desc, :price]
# File lib/sequel/dataset/query.rb, line 1064 1064: def invert_order(order) 1065: return nil unless order 1066: new_order = [] 1067: order.map do |f| 1068: case f 1069: when SQL::OrderedExpression 1070: f.invert 1071: else 1072: SQL::OrderedExpression.new(f) 1073: end 1074: end 1075: end
SQL fragment specifying a JOIN type, converts underscores to spaces and upcases.
# File lib/sequel/dataset/sql.rb, line 996 996: def join_type_sql(join_type) 997: "#{join_type.to_s.gsub(UNDERSCORE, SPACE).upcase} JOIN" 998: end
Whether this dataset is a joined dataset
# File lib/sequel/dataset/sql.rb, line 1001 1001: def joined_dataset? 1002: (opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join] 1003: end
SQL fragment for Array. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.
# File lib/sequel/dataset/sql.rb, line 1006 1006: def literal_array_append(sql, v) 1007: if Sequel.condition_specifier?(v) 1008: literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v)) 1009: else 1010: array_sql_append(sql, v) 1011: end 1012: end
SQL fragment for BigDecimal
# File lib/sequel/dataset/sql.rb, line 1015 1015: def literal_big_decimal(v) 1016: d = v.to_s("F") 1017: v.nan? || v.infinite? ? "'#{d}'" : d 1018: end
Use the driver’s escape_bytea
# File lib/sequel/adapters/postgres.rb, line 743 743: def literal_blob_append(sql, v) 744: sql << APOS << db.synchronize{|c| c.escape_bytea(v)} << APOS 745: end
SQL fragment for Date, using the ISO8601 format.
# File lib/sequel/dataset/sql.rb, line 1033 1033: def literal_date(v) 1034: if requires_sql_standard_datetimes? 1035: v.strftime(FORMAT_DATE_STANDARD) 1036: else 1037: v.strftime(FORMAT_DATE) 1038: end 1039: end
SQL fragment for DateTime
# File lib/sequel/dataset/sql.rb, line 1042 1042: def literal_datetime(v) 1043: format_timestamp(v) 1044: end
SQL fragment for SQL::Expression, result depends on the specific type of expression.
# File lib/sequel/dataset/sql.rb, line 1047 1047: def literal_expression_append(sql, v) 1048: v.to_s_append(self, sql) 1049: end
SQL fragment for false
# File lib/sequel/dataset/sql.rb, line 1052 1052: def literal_false 1053: BOOL_FALSE 1054: end
SQL fragment for Float
# File lib/sequel/dataset/sql.rb, line 1057 1057: def literal_float(v) 1058: v.to_s 1059: end
SQL fragment for Integer
# File lib/sequel/dataset/sql.rb, line 1067 1067: def literal_integer(v) 1068: v.to_s 1069: end
SQL fragment for nil
# File lib/sequel/dataset/sql.rb, line 1072 1072: def literal_nil 1073: NULL 1074: end
SQL fragment for a type of object not handled by Dataset#literal. Calls sql_literal if object responds to it, otherwise raises an error. Classes implementing sql_literal should call a class-specific method on the dataset provided and should add that method to Sequel::Dataset, allowing for adapters to provide customized literalizations. If a database specific type is allowed, this should be overriden in a subclass.
# File lib/sequel/dataset/sql.rb, line 1082 1082: def literal_other_append(sql, v) 1083: if v.respond_to?(:sql_literal_append) 1084: v.sql_literal_append(self, sql) 1085: elsif v.respond_to?(:sql_literal) 1086: sql << v.sql_literal(self) 1087: else 1088: raise Error, "can't express #{v.inspect} as a SQL literal" 1089: end 1090: end
# File lib/sequel/adapters/oracle.rb, line 415 415: def literal_other_append(sql, v) 416: case v 417: when OraDate 418: literal_append(sql, db.to_application_timestamp(v)) 419: when OCI8::CLOB 420: v.rewind 421: literal_append(sql, v.read) 422: else 423: super 424: end 425: end
SQL fragment for Sequel::SQLTime, containing just the time part
# File lib/sequel/dataset/sql.rb, line 1093 1093: def literal_sqltime(v) 1094: v.strftime("'%H:%M:%S#{format_timestamp_usec(v.usec) if supports_timestamp_usecs?}'") 1095: end
Use the driver’s escape_string
# File lib/sequel/adapters/postgres.rb, line 748 748: def literal_string_append(sql, v) 749: sql << APOS << db.synchronize{|c| c.escape_string(v)} << APOS 750: end
Handle correct quoting of strings using ::MySQL.quote.
# File lib/sequel/adapters/mysql.rb, line 348 348: def literal_string_append(sql, v) 349: sql << "'" 350: sql << ::Mysql.quote(v) 351: sql << "'" 352: end
Converts a symbol into a column name. This method supports underscore notation in order to express qualified (two underscores) and aliased (three underscores) columns:
dataset.literal(:abc) #=> "abc" dataset.literal(:abc___a) #=> "abc AS a" dataset.literal(:items__abc) #=> "items.abc" dataset.literal(:items__abc___a) #=> "items.abc AS a"
# File lib/sequel/dataset/sql.rb, line 1110 1110: def literal_symbol_append(sql, v) 1111: c_table, column, c_alias = split_symbol(v) 1112: if c_table 1113: quote_identifier_append(sql, c_table) 1114: sql << DOT 1115: end 1116: quote_identifier_append(sql, column) 1117: as_sql_append(sql, c_alias) if c_alias 1118: end
SQL fragment for Time
# File lib/sequel/dataset/sql.rb, line 1121 1121: def literal_time(v) 1122: format_timestamp(v) 1123: end
SQL fragment for true
# File lib/sequel/dataset/sql.rb, line 1126 1126: def literal_true 1127: BOOL_TRUE 1128: end
Modify the receiver with the results of sending the meth, args, and block to the receiver and merging the options of the resulting dataset into the receiver’s options.
# File lib/sequel/dataset/mutation.rb, line 54 54: def mutation_method(meth, *args, &block) 55: copy = send(meth, *args, &block) 56: @opts.merge!(copy.opts) 57: self 58: end
Whether using an offset returns an extra row number column that should be eliminated, false by default.
# File lib/sequel/dataset/features.rb, line 159 159: def offset_returns_row_number_column? 160: false 161: end
Modify the identifier returned from the database based on the identifier_output_method.
# File lib/sequel/dataset/actions.rb, line 786 786: def output_identifier(v) 787: v = 'untitled' if v == '' 788: (i = identifier_output_method) ? v.to_s.send(i).to_sym : v.to_sym 789: end
This is run inside .all, after all of the records have been loaded via .each, but before any block passed to all is called. It is called with a single argument, an array of all returned records. Does nothing by default, added to make the model eager loading code simpler.
# File lib/sequel/dataset/actions.rb, line 795 795: def post_load(all_records) 796: end
# File lib/sequel/adapters/oracle.rb, line 427 427: def prepared_arg_placeholder 428: PREPARED_ARG_PLACEHOLDER 429: end
The argument placeholder. Most databases used unnumbered arguments with question marks, so that is the default.
# File lib/sequel/dataset/prepared_statements.rb, line 273 273: def prepared_arg_placeholder 274: PREPARED_ARG_PLACEHOLDER 275: end
Returns a qualified column name (including a table name) if the column name isn’t already qualified.
# File lib/sequel/dataset/sql.rb, line 1132 1132: def qualified_column_name(column, table) 1133: if Symbol === column 1134: c_table, column, c_alias = split_symbol(column) 1135: unless c_table 1136: case table 1137: when Symbol 1138: schema, table, t_alias = split_symbol(table) 1139: t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema 1140: when Sequel::SQL::AliasedExpression 1141: t_alias = table.aliaz 1142: end 1143: c_table = t_alias || table 1144: end 1145: ::Sequel::SQL::QualifiedIdentifier.new(c_table, column) 1146: else 1147: column 1148: end 1149: end
Qualify the given expression e to the given table.
# File lib/sequel/dataset/sql.rb, line 1152 1152: def qualified_expression(e, table) 1153: Qualifier.new(self, table).transform(e) 1154: end
Called by insert/update/delete when returning is used. Yields each row as a plain hash to the block if one is given, or returns an array of plain hashes for all rows if a block is not given
# File lib/sequel/dataset/actions.rb, line 801 801: def returning_fetch_rows(sql, &block) 802: if block 803: default_server.fetch_rows(sql, &block) 804: nil 805: else 806: rows = [] 807: default_server.fetch_rows(sql){|r| rows << r} 808: rows 809: end 810: end
Modify the sql to add the columns selected
# File lib/sequel/dataset/sql.rb, line 1162 1162: def select_columns_sql(sql) 1163: sql << SPACE 1164: column_list_append(sql, @opts[:select]) 1165: end
Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn’t work on all databases. I consider this an ugly hack, but can’t I think of a better default.
# File lib/sequel/dataset/sql.rb, line 1182 1182: def select_compounds_sql(sql) 1183: return unless c = @opts[:compounds] 1184: c.each do |type, dataset, all| 1185: sql << SPACE << type.to_s.upcase 1186: sql << ALL if all 1187: sql << SPACE 1188: compound_dataset_sql_append(sql, dataset) 1189: end 1190: end
Modify the sql to add the DISTINCT modifier
# File lib/sequel/dataset/sql.rb, line 1168 1168: def select_distinct_sql(sql) 1169: if distinct = @opts[:distinct] 1170: sql << DISTINCT 1171: unless distinct.empty? 1172: sql << ON_PAREN 1173: expression_list_append(sql, distinct) 1174: sql << PAREN_CLOSE 1175: end 1176: end 1177: end
Modify the sql to add the list of tables to select FROM
# File lib/sequel/dataset/sql.rb, line 1193 1193: def select_from_sql(sql) 1194: if f = @opts[:from] 1195: sql << FROM 1196: source_list_append(sql, f) 1197: end 1198: end
Modify the sql to add the expressions to GROUP BY
# File lib/sequel/dataset/sql.rb, line 1202 1202: def select_group_sql(sql) 1203: if group = @opts[:group] 1204: sql << GROUP_BY 1205: if go = @opts[:group_options] 1206: if uses_with_rollup? 1207: expression_list_append(sql, group) 1208: sql << SPACE_WITH << go.to_s.upcase 1209: else 1210: sql << go.to_s.upcase << PAREN_OPEN 1211: expression_list_append(sql, group) 1212: sql << PAREN_CLOSE 1213: end 1214: else 1215: expression_list_append(sql, group) 1216: end 1217: end 1218: end
Modify the sql to add the filter criteria in the HAVING clause
# File lib/sequel/dataset/sql.rb, line 1221 1221: def select_having_sql(sql) 1222: if having = @opts[:having] 1223: sql << HAVING 1224: literal_append(sql, having) 1225: end 1226: end
Modify the sql to add the list of tables to JOIN to
# File lib/sequel/dataset/sql.rb, line 1229 1229: def select_join_sql(sql) 1230: if js = @opts[:join] 1231: js.each{|j| literal_append(sql, j)} 1232: end 1233: end
Modify the sql to limit the number of rows returned and offset
# File lib/sequel/dataset/sql.rb, line 1236 1236: def select_limit_sql(sql) 1237: if l = @opts[:limit] 1238: sql << LIMIT 1239: literal_append(sql, l) 1240: end 1241: if o = @opts[:offset] 1242: sql << OFFSET 1243: literal_append(sql, o) 1244: end 1245: end
Modify the sql to support the different types of locking modes.
# File lib/sequel/dataset/sql.rb, line 1248 1248: def select_lock_sql(sql) 1249: case l = @opts[:lock] 1250: when :update 1251: sql << FOR_UPDATE 1252: when String 1253: sql << SPACE << l 1254: end 1255: end
Modify the sql to add the expressions to ORDER BY
# File lib/sequel/dataset/sql.rb, line 1258 1258: def select_order_sql(sql) 1259: if o = @opts[:order] 1260: sql << ORDER_BY 1261: expression_list_append(sql, o) 1262: end 1263: end
# File lib/sequel/dataset/sql.rb, line 1267 1267: def select_select_sql(sql) 1268: sql << SELECT 1269: end
Modify the sql to add the filter criteria in the WHERE clause
# File lib/sequel/dataset/sql.rb, line 1272 1272: def select_where_sql(sql) 1273: if w = @opts[:where] 1274: sql << WHERE 1275: literal_append(sql, w) 1276: end 1277: end
SQL Fragment specifying the WITH clause
# File lib/sequel/dataset/sql.rb, line 1282 1282: def select_with_sql(sql) 1283: ws = opts[:with] 1284: return if !ws || ws.empty? 1285: sql << select_with_sql_base 1286: c = false 1287: comma = COMMA 1288: ws.each do |w| 1289: sql << comma if c 1290: quote_identifier_append(sql, w[:name]) 1291: if args = w[:args] 1292: sql << PAREN_OPEN 1293: argument_list_append(sql, args) 1294: sql << PAREN_CLOSE 1295: end 1296: sql << AS 1297: literal_dataset_append(sql, w[:dataset]) 1298: c ||= true 1299: end 1300: sql << SPACE 1301: end
The base keyword to use for the SQL WITH clause
# File lib/sequel/dataset/sql.rb, line 1307 1307: def select_with_sql_base 1308: SQL_WITH 1309: end
Converts an array of source names into into a comma separated list.
# File lib/sequel/dataset/sql.rb, line 1312 1312: def source_list_append(sql, sources) 1313: raise(Error, 'No source specified for query') if sources.nil? || sources == [] 1314: c = false 1315: co = COMMA 1316: sources.each do |s| 1317: sql << co if c 1318: identifier_append(sql, s) 1319: c ||= true 1320: end 1321: end
Splits the symbol into three parts. Each part will either be a string or nil.
For columns, these parts are the table, column, and alias. For tables, these parts are the schema, table, and alias.
# File lib/sequel/dataset/sql.rb, line 1328 1328: def split_symbol(sym) 1329: case s = sym.to_s 1330: when COLUMN_REF_RE1 1331: [$1, $2, $3] 1332: when COLUMN_REF_RE2 1333: [nil, $1, $2] 1334: when COLUMN_REF_RE3 1335: [$1, $2, nil] 1336: else 1337: [nil, s, nil] 1338: end 1339: end
The string that is appended to to create the SQL query, the empty string by default
# File lib/sequel/dataset/sql.rb, line 1343 1343: def sql_string_origin 1344: '' 1345: end
SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings.
# File lib/sequel/dataset/sql.rb, line 1350 1350: def static_sql(sql) 1351: if append_sql = @opts[:append_sql] 1352: if sql.is_a?(String) 1353: append_sql << sql 1354: else 1355: literal_append(append_sql, sql) 1356: end 1357: else 1358: if sql.is_a?(String) 1359: sql 1360: else 1361: literal(sql) 1362: end 1363: end 1364: end
Return the unaliased part of the identifier. Handles both implicit aliases in symbols, as well as SQL::AliasedExpression objects. Other objects are returned as is.
# File lib/sequel/dataset/actions.rb, line 815 815: def unaliased_identifier(c) 816: case c 817: when Symbol 818: c_table, column, _ = split_symbol(c) 819: c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym 820: when SQL::AliasedExpression 821: c.expression 822: when SQL::OrderedExpression 823: expr = c.expression 824: if expr.is_a?(Symbol) 825: expr = unaliased_identifier(expr) 826: SQL::OrderedExpression.new(unaliased_identifier(c.expression), c.descending, :nulls=>c.nulls) 827: else 828: c 829: end 830: else 831: c 832: end 833: end
The SQL fragment specifying the columns and values to SET.
# File lib/sequel/dataset/sql.rb, line 1385 1385: def update_set_sql(sql) 1386: values = opts[:values] 1387: sql << SET 1388: if values.is_a?(Hash) 1389: values = opts[:defaults].merge(values) if opts[:defaults] 1390: values = values.merge(opts[:overrides]) if opts[:overrides] 1391: c = false 1392: eq = EQUAL 1393: values.each do |k, v| 1394: sql << COMMA if c 1395: if k.is_a?(String) && !k.is_a?(LiteralString) 1396: quote_identifier_append(sql, k) 1397: else 1398: literal_append(sql, k) 1399: end 1400: sql << eq 1401: literal_append(sql, v) 1402: c ||= true 1403: end 1404: else 1405: sql << values 1406: end 1407: end
SQL fragment specifying the tables from with to delete. Includes join table if modifying joins is allowed.
# File lib/sequel/dataset/sql.rb, line 1378 1378: def update_table_sql(sql) 1379: sql << SPACE 1380: source_list_append(sql, @opts[:from]) 1381: select_join_sql(sql) if supports_modifying_joins? 1382: end
# File lib/sequel/dataset/sql.rb, line 1409 1409: def update_update_sql(sql) 1410: sql << UPDATE 1411: end
Whether the RETURNING clause is used for the given dataset. type can be :insert, :update, or :delete.
# File lib/sequel/dataset/features.rb, line 165 165: def uses_returning?(type) 166: opts[:returning] && !@opts[:sql] && supports_returning?(type) 167: end
Whether the dataset uses WITH ROLLUP/CUBE instead of ROLLUP()/CUBE().
# File lib/sequel/dataset/features.rb, line 170 170: def uses_with_rollup? 171: false 172: end
Treat the block as a virtual_row block if not nil and add the resulting columns to the columns array (modifies columns).
# File lib/sequel/dataset/query.rb, line 1085 1085: def virtual_row_columns(columns, block) 1086: columns.concat(Array(Sequel.virtual_row(&block))) if block 1087: end
For each row in the result set, yield a hash with column name symbol keys and typecasted values.
# File lib/sequel/adapters/postgres.rb, line 754 754: def yield_hash_rows(res, cols) 755: res.ntuples.times do |recnum| 756: converted_rec = {} 757: cols.each do |fieldnum, type_proc, fieldsym| 758: value = res.getvalue(recnum, fieldnum) 759: converted_rec[fieldsym] = (value && type_proc) ? type_proc.call(value) : value 760: end 761: yield converted_rec 762: end 763: end
Yield each row of the given result set r with columns cols as a hash with symbol keys
# File lib/sequel/adapters/mysql.rb, line 356 356: def yield_rows(r, cols) 357: while row = r.fetch_row 358: h = {} 359: cols.each{|n, p, i| v = row[i]; h[n] = (v && p) ? p.call(v) : v} 360: yield h 361: end 362: end
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