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.
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: else 14: @quote_identifiers = db.quote_identifiers? 15: end 16: end
Whether you must use a column alias list for recursive CTEs (false by default).
# File lib/sequel/dataset/features.rb, line 27 27: def recursive_cte_requires_column_aliases? 28: false 29: end
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer)
# File lib/sequel/dataset/features.rb, line 39 39: def requires_placeholder_type_specifiers? 40: false 41: 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 46 46: def supports_cte?(type=:select) 47: send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_with_sql""#{type}_with_sql") 48: 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 53 53: def supports_cte_in_subqueries? 54: false 55: end
Whether the dataset supports the IS TRUE syntax.
# File lib/sequel/dataset/features.rb, line 89 89: def supports_is_true? 90: true 91: end
Whether the dataset supports the JOIN table USING (column1, …) syntax.
# File lib/sequel/dataset/features.rb, line 94 94: def supports_join_using? 95: true 96: end
Whether modifying joined datasets is supported.
# File lib/sequel/dataset/features.rb, line 99 99: def supports_modifying_joins? 100: false 101: end
Whether the dataset supports pattern matching by regular expressions.
# File lib/sequel/dataset/features.rb, line 116 116: def supports_regexp? 117: false 118: end
Whether the dataset supports REPLACE syntax, false by default.
# File lib/sequel/dataset/features.rb, line 121 121: def supports_replace? 122: false 123: 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 127 127: def supports_returning?(type) 128: send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_returning_sql""#{type}_returning_sql") 129: end
Whether the database supports SELECT *, column FROM table
# File lib/sequel/dataset/features.rb, line 132 132: def supports_select_all_and_column? 133: true 134: end
Whether the dataset supports timezones in literal timestamps
# File lib/sequel/dataset/features.rb, line 137 137: def supports_timestamp_timezones? 138: false 139: end
Whether the dataset supports fractional seconds in literal timestamps
# File lib/sequel/dataset/features.rb, line 142 142: def supports_timestamp_usecs? 143: true 144: end
On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the "Prepared Statements/Bound Variables" guide.
PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('?').freeze |
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=>:$id).bind(:id=>1).call(:first) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 219 219: def bind(bind_vars={}) 220: clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars) 221: end
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.
DB[:table].filter(:id=>:$id).call(:first, :id=>1) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 230 230: def call(type, bind_variables={}, *values, &block) 231: prepare(type, nil, *values).call(bind_variables, &block) 232: end
Prepare an SQL statement for later execution. Takes a type similar to call, 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 252 252: def prepare(type, name=nil, *values) 253: ps = to_prepared_statement(type, values) 254: db.set_prepared_statement(name, ps) if name 255: ps 256: 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 262 262: def to_prepared_statement(type, values=nil) 263: ps = bind 264: ps.extend(PreparedStatementMethods) 265: ps.orig_dataset = self 266: ps.prepared_type = type 267: ps.prepared_modify_values = values 268: ps 269: end
Dataset graphing changes the dataset to yield hashes where keys are table name symbols and values are hashes representing the columns related to that table. All of these methods return modified copies of the receiver.
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
# File lib/sequel/dataset/graph.rb, line 16 16: def add_graph_aliases(graph_aliases) 17: unless (ga = opts[:graph_aliases]) || (opts[:graph] && (ga = opts[:graph][:column_aliases])) 18: raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases" 19: end 20: columns, graph_aliases = graph_alias_columns(graph_aliases) 21: select_more(*columns).clone(:graph_aliases => ga.merge(graph_aliases)) 22: end
Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.
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_table. |
:join_type : | The type of join to use (passed to join_table). Defaults to :left_outer. |
:qualify: | The type of qualification to do, see join_table. |
: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 49 49: def graph(dataset, join_conditions = nil, options = OPTS, &block) 50: # Allow the use of a dataset or symbol as the first argument 51: # Find the table name/dataset based on the argument 52: table_alias = options[:table_alias] 53: case dataset 54: when Symbol 55: table = dataset 56: dataset = @db[dataset] 57: table_alias ||= table 58: when ::Sequel::Dataset 59: if dataset.simple_select_all? 60: table = dataset.opts[:from].first 61: table_alias ||= table 62: else 63: table = dataset 64: table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1) 65: end 66: else 67: raise Error, "The dataset argument should be a symbol or dataset" 68: end 69: 70: # Raise Sequel::Error with explanation that the table alias has been used 71: raise_alias_error = lambda do 72: raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \ 73: "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 74: end 75: 76: # Only allow table aliases that haven't been used 77: raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) 78: 79: # Use a from_self if this is already a joined table 80: ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self 81: 82: # Join the table early in order to avoid cloning the dataset twice 83: ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], :qualify=>options[:qualify], &block) 84: opts = ds.opts 85: 86: # Whether to include the table in the result set 87: add_table = options[:select] == false ? false : true 88: # Whether to add the columns to the list of column aliases 89: add_columns = !ds.opts.include?(:graph_aliases) 90: 91: # Setup the initial graph data structure if it doesn't exist 92: if graph = opts[:graph] 93: opts[:graph] = graph = graph.dup 94: select = opts[:select].dup 95: [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup} 96: else 97: master = alias_symbol(ds.first_source_alias) 98: raise_alias_error.call if master == table_alias 99: # Master hash storing all .graph related information 100: graph = opts[:graph] = {} 101: # Associates column aliases back to tables and columns 102: column_aliases = graph[:column_aliases] = {} 103: # Associates table alias (the master is never aliased) 104: table_aliases = graph[:table_aliases] = {master=>self} 105: # Keep track of the alias numbers used 106: ca_num = graph[:column_alias_num] = Hash.new(0) 107: # All columns in the master table are never 108: # aliased, but are not included if set_graph_aliases 109: # has been used. 110: if add_columns 111: if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll))) 112: select = select.each do |sel| 113: column = case sel 114: when Symbol 115: _, c, a = split_symbol(sel) 116: (a || c).to_sym 117: when SQL::Identifier 118: sel.value.to_sym 119: when SQL::QualifiedIdentifier 120: column = sel.column 121: column = column.value if column.is_a?(SQL::Identifier) 122: column.to_sym 123: when SQL::AliasedExpression 124: column = sel.aliaz 125: column = column.value if column.is_a?(SQL::Identifier) 126: column.to_sym 127: else 128: raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" 129: end 130: column_aliases[column] = [master, column] 131: end 132: select = qualified_expression(select, master) 133: else 134: select = columns.map do |column| 135: column_aliases[column] = [master, column] 136: SQL::QualifiedIdentifier.new(master, column) 137: end 138: end 139: end 140: end 141: 142: # Add the table alias to the list of aliases 143: # Even if it isn't been used in the result set, 144: # we add a key for it with a nil value so we can check if it 145: # is used more than once 146: table_aliases = graph[:table_aliases] 147: table_aliases[table_alias] = add_table ? dataset : nil 148: 149: # Add the columns to the selection unless we are ignoring them 150: if add_table && add_columns 151: column_aliases = graph[:column_aliases] 152: ca_num = graph[:column_alias_num] 153: # Which columns to add to the result set 154: cols = options[:select] || dataset.columns 155: # If the column hasn't been used yet, don't alias it. 156: # If it has been used, try table_column. 157: # If that has been used, try table_column_N 158: # using the next value of N that we know hasn't been 159: # used 160: cols.each do |column| 161: col_alias, identifier = if column_aliases[column] 162: column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}" 163: if column_aliases[column_alias] 164: column_alias_num = ca_num[column_alias] 165: column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}" 166: ca_num[column_alias] += 1 167: end 168: [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)] 169: else 170: ident = SQL::QualifiedIdentifier.new(table_alias, column) 171: [column, ident] 172: end 173: column_aliases[col_alias] = [table_alias, column] 174: select.push(identifier) 175: end 176: end 177: add_columns ? ds.select(*select) : ds 178: 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 ...
# File lib/sequel/dataset/graph.rb, line 203 203: def set_graph_aliases(graph_aliases) 204: columns, graph_aliases = graph_alias_columns(graph_aliases) 205: ds = select(*columns) 206: ds.opts[:graph_aliases] = graph_aliases 207: ds 208: end
MUTATION_METHODS | = | QUERY_METHODS - [:paginate, :naked, :from_self] | All methods that should have a ! method added that modifies the receiver. |
identifier_input_method | [W] | Set the method to call on identifiers going into the database for this dataset |
identifier_output_method | [W] | Set the method to call on identifiers coming the database for this dataset |
quote_identifiers | [W] | Whether to quote identifiers for this dataset |
row_proc | [RW] | The row_proc for this database, should be any object that responds to call with a single hash argument and returns the object you want each to return. |
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.
Do not call this method with untrusted input, as that can result in arbitrary code execution.
# File lib/sequel/dataset/mutation.rb, line 17 17: def self.def_mutation_method(*meths) 18: options = meths.pop if meths.last.is_a?(Hash) 19: mod = options[:module] if options 20: mod ||= self 21: meths.each do |meth| 22: mod.class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__) 23: end 24: end
Load an extension into the receiver. In addition to requiring the extension file, this also modifies the dataset to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.
# File lib/sequel/dataset/mutation.rb, line 47 47: def extension!(*exts) 48: Sequel.extension(*exts) 49: exts.each do |ext| 50: if pr = Sequel.synchronize{EXTENSIONS[ext]} 51: pr.call(self) 52: else 53: raise(Error, "Extension #{ext} does not have specific support handling individual datasets") 54: end 55: end 56: self 57: end
These methods don‘t fit cleanly into another section.
NOTIMPL_MSG | = | "This method must be overridden in Sequel adapters".freeze |
ARRAY_ACCESS_ERROR_MSG | = | 'You cannot call Dataset#[] with an integer or with no arguments.'.freeze |
ARG_BLOCK_ERROR_MSG | = | 'Must use either an argument or a block, not both'.freeze |
IMPORT_ERROR_MSG | = | 'Using Sequel::Dataset#import an empty column array is not allowed'.freeze |
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) 29: @db = db 30: @opts = OPTS 31: 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 the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:
ds.escape_like("foo\\%_") # 'foo\\\%\_'
# File lib/sequel/dataset/misc.rb, line 58 58: def escape_like(string) 59: string.gsub(/[\\%_]/){|m| "\\#{m}"} 60: end
Alias of first_source_alias
# File lib/sequel/dataset/misc.rb, line 63 63: def first_source 64: first_source_alias 65: 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 75 75: def first_source_alias 76: source = @opts[:from] 77: if source.nil? || source.empty? 78: raise Error, 'No source specified for query' 79: end 80: case s = source.first 81: when SQL::AliasedExpression 82: s.aliaz 83: when Symbol 84: _, _, aliaz = split_symbol(s) 85: aliaz ? aliaz.to_sym : s 86: else 87: s 88: end 89: 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 100 100: def first_source_table 101: source = @opts[:from] 102: if source.nil? || source.empty? 103: raise Error, 'No source specified for query' 104: end 105: case s = source.first 106: when SQL::AliasedExpression 107: s.expression 108: when Symbol 109: sch, table, aliaz = split_symbol(s) 110: aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s 111: else 112: s 113: end 114: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 124 124: def identifier_input_method 125: if defined?(@identifier_input_method) 126: @identifier_input_method 127: else 128: @identifier_input_method = db.identifier_input_method 129: end 130: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 134 134: def identifier_output_method 135: if defined?(@identifier_output_method) 136: @identifier_output_method 137: else 138: @identifier_output_method = db.identifier_output_method 139: end 140: 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 159 159: def split_alias(c) 160: case c 161: when Symbol 162: c_table, column, aliaz = split_symbol(c) 163: [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz] 164: when SQL::AliasedExpression 165: [c.expression, c.aliaz] 166: when SQL::JoinClause 167: [c.table, c.table_alias] 168: else 169: [c, nil] 170: end 171: 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 195 195: def unused_table_alias(table_alias, used_aliases = []) 196: table_alias = alias_symbol(table_alias) 197: used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from] 198: used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join] 199: if used_aliases.include?(table_alias) 200: i = 0 201: loop do 202: ta = "#{table_alias}_#{i}""#{table_alias}_#{i}" 203: return ta unless used_aliases.include?(ta) 204: i += 1 205: end 206: else 207: table_alias 208: end 209: 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 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
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: values = [] 44: vals.each do |k,v| 45: columns << k 46: values << v 47: end 48: when Dataset, Array, LiteralString 49: values = vals 50: end 51: when 2 52: if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString)) 53: columns, values = v0, v1 54: raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length 55: end 56: end 57: 58: if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 59: columns = [columns().last] 60: values = [DEFAULT] 61: end 62: clone(:columns=>columns, :values=>values)._insert_sql 63: 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 75 75: def literal_append(sql, v) 76: case v 77: when Symbol 78: literal_symbol_append(sql, v) 79: when String 80: case v 81: when LiteralString 82: sql << v 83: when SQL::Blob 84: literal_blob_append(sql, v) 85: else 86: literal_string_append(sql, v) 87: end 88: when Integer 89: sql << literal_integer(v) 90: when Hash 91: literal_hash_append(sql, v) 92: when SQL::Expression 93: literal_expression_append(sql, v) 94: when Float 95: sql << literal_float(v) 96: when BigDecimal 97: sql << literal_big_decimal(v) 98: when NilClass 99: sql << literal_nil 100: when TrueClass 101: sql << literal_true 102: when FalseClass 103: sql << literal_false 104: when Array 105: literal_array_append(sql, v) 106: when Time 107: sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v)) 108: when DateTime 109: sql << literal_datetime(v) 110: when Date 111: sql << literal_date(v) 112: when Dataset 113: literal_dataset_append(sql, v) 114: else 115: literal_other_append(sql, v) 116: end 117: 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 125 125: def multi_insert_sql(columns, values) 126: values.map{|r| insert_sql(columns, r)} 127: end
Same as select_sql, not aliased directly to make subclassing simpler.
# File lib/sequel/dataset/sql.rb, line 138 138: def sql 139: select_sql 140: end
Returns a TRUNCATE SQL query string. See truncate
DB[:items].truncate_sql # => 'TRUNCATE items'
# File lib/sequel/dataset/sql.rb, line 145 145: def truncate_sql 146: if opts[:sql] 147: static_sql(opts[:sql]) 148: else 149: check_truncation_allowed! 150: raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having] 151: t = '' 152: source_list_append(t, opts[:from]) 153: _truncate_sql(t) 154: end 155: 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 164 164: def update_sql(values = OPTS) 165: return static_sql(opts[:sql]) if opts[:sql] 166: check_modification_allowed! 167: clone(:values=>values)._update_sql 168: end
These methods, while public, are not designed to be used directly by the end user.
EMULATED_FUNCTION_MAP | = | {} | Map of emulated function names to native function names. | |
WILDCARD | = | LiteralString.new('*').freeze | ||
ALL | = | ' ALL'.freeze | ||
AND_SEPARATOR | = | " AND ".freeze | ||
APOS | = | "'".freeze | ||
APOS_RE | = | /'/.freeze | ||
ARRAY_EMPTY | = | '(NULL)'.freeze | ||
AS | = | ' AS '.freeze | ||
ASC | = | ' ASC'.freeze | ||
BACKSLASH | = | "\\".freeze | ||
BOOL_FALSE | = | "'f'".freeze | ||
BOOL_TRUE | = | "'t'".freeze | ||
BRACKET_CLOSE | = | ']'.freeze | ||
BRACKET_OPEN | = | '['.freeze | ||
CASE_ELSE | = | " ELSE ".freeze | ||
CASE_END | = | " END)".freeze | ||
CASE_OPEN | = | '(CASE'.freeze | ||
CASE_THEN | = | " THEN ".freeze | ||
CASE_WHEN | = | " WHEN ".freeze | ||
CAST_OPEN | = | 'CAST('.freeze | ||
COLON | = | ':'.freeze | ||
COLUMN_REF_RE1 | = | Sequel::COLUMN_REF_RE1 | ||
COLUMN_REF_RE2 | = | Sequel::COLUMN_REF_RE2 | ||
COLUMN_REF_RE3 | = | Sequel::COLUMN_REF_RE3 | ||
COMMA | = | ', '.freeze | ||
COMMA_SEPARATOR | = | COMMA | ||
CONDITION_FALSE | = | '(1 = 0)'.freeze | ||
CONDITION_TRUE | = | '(1 = 1)'.freeze | ||
COUNT_FROM_SELF_OPTS | = | [:distinct, :group, :sql, :limit, :offset, :compounds] | ||
COUNT_OF_ALL_AS_COUNT | = | SQL::Function.new(:count, WILDCARD).as(:count) | ||
DATASET_ALIAS_BASE_NAME | = | 't'.freeze | ||
DEFAULT | = | LiteralString.new('DEFAULT').freeze | ||
DEFAULT_VALUES | = | " DEFAULT VALUES".freeze | ||
DELETE | = | 'DELETE'.freeze | ||
DELETE_CLAUSE_METHODS | = | clause_methods(:delete, %w'delete from where') | ||
DESC | = | ' DESC'.freeze | ||
DISTINCT | = | " DISTINCT".freeze | ||
DOT | = | '.'.freeze | ||
DOUBLE_APOS | = | "''".freeze | ||
DOUBLE_QUOTE | = | '""'.freeze | ||
EQUAL | = | ' = '.freeze | ||
ESCAPE | = | " ESCAPE ".freeze | ||
EXTRACT | = | 'extract('.freeze | ||
EXISTS | = | ['EXISTS '.freeze].freeze | ||
FOR_UPDATE | = | ' FOR UPDATE'.freeze | ||
FORMAT_DATE | = | "'%Y-%m-%d'".freeze | ||
FORMAT_DATE_STANDARD | = | "DATE '%Y-%m-%d'".freeze | ||
FORMAT_OFFSET | = | "%+03i%02i".freeze | ||
FORMAT_TIMESTAMP_RE | = | /%[Nz]/.freeze | ||
FORMAT_TIMESTAMP_USEC | = | ".%06d".freeze | ||
FORMAT_USEC | = | '%N'.freeze | ||
FRAME_ALL | = | "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING".freeze | ||
FRAME_ROWS | = | "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW".freeze | ||
FROM | = | ' FROM '.freeze | ||
FUNCTION_EMPTY | = | '()'.freeze | ||
GROUP_BY | = | " GROUP BY ".freeze | ||
HAVING | = | " HAVING ".freeze | ||
INSERT | = | "INSERT".freeze | ||
INSERT_CLAUSE_METHODS | = | clause_methods(:insert, %w'insert into columns values') | ||
INTO | = | " INTO ".freeze | ||
IS_LITERALS | = | {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze | ||
IS_OPERATORS | = | ::Sequel::SQL::ComplexExpression::IS_OPERATORS | ||
LIKE_OPERATORS | = | ::Sequel::SQL::ComplexExpression::LIKE_OPERATORS | ||
LIMIT | = | " LIMIT ".freeze | ||
N_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS | ||
NOT_SPACE | = | 'NOT '.freeze | ||
NULL | = | "NULL".freeze | ||
NULLS_FIRST | = | " NULLS FIRST".freeze | ||
NULLS_LAST | = | " NULLS LAST".freeze | ||
OFFSET | = | " OFFSET ".freeze | ||
ON | = | ' ON '.freeze | ||
ON_PAREN | = | " ON (".freeze | ||
ORDER_BY | = | " ORDER BY ".freeze | ||
ORDER_BY_NS | = | "ORDER BY ".freeze | ||
OVER | = | ' OVER '.freeze | ||
PAREN_CLOSE | = | ')'.freeze | ||
PAREN_OPEN | = | '('.freeze | ||
PAREN_SPACE_OPEN | = | ' ('.freeze | ||
PARTITION_BY | = | "PARTITION BY ".freeze | ||
QUALIFY_KEYS | = | [:select, :where, :having, :order, :group] | ||
QUESTION_MARK | = | '?'.freeze | ||
QUESTION_MARK_RE | = | /\?/.freeze | ||
QUOTE | = | '"'.freeze | ||
QUOTE_RE | = | /"/.freeze | ||
RETURNING | = | " RETURNING ".freeze | ||
SELECT | = | 'SELECT'.freeze | ||
SELECT_CLAUSE_METHODS | = | clause_methods(:select, %w'with select distinct columns from join where group having compounds order limit lock') | ||
SET | = | ' SET '.freeze | ||
SPACE | = | ' '.freeze | ||
SQL_WITH | = | "WITH ".freeze | ||
SPACE_WITH | = | " WITH ".freeze | ||
TILDE | = | '~'.freeze | ||
TIMESTAMP_FORMAT | = | "'%Y-%m-%d %H:%M:%S%N%z'".freeze | ||
STANDARD_TIMESTAMP_FORMAT | = | "TIMESTAMP #{TIMESTAMP_FORMAT}".freeze | ||
TWO_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS | ||
REGEXP_OPERATORS | = | ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS | ||
UNDERSCORE | = | '_'.freeze | ||
UPDATE | = | 'UPDATE'.freeze | ||
UPDATE_CLAUSE_METHODS | = | clause_methods(:update, %w'update table set where') | ||
USING | = | ' USING ('.freeze | ||
VALUES | = | " VALUES ".freeze | ||
V190 | = | '1.9.0'.freeze | ||
WHERE | = | " WHERE ".freeze |
SQL fragment for BooleanConstants
# File lib/sequel/dataset/sql.rb, line 316 316: def boolean_constant_sql_append(sql, constant) 317: if (constant == true || constant == false) && !supports_where_true? 318: sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE) 319: else 320: literal_append(sql, constant) 321: end 322: end
SQL fragment for CaseExpression
# File lib/sequel/dataset/sql.rb, line 325 325: def case_expression_sql_append(sql, ce) 326: sql << CASE_OPEN 327: if ce.expression? 328: sql << SPACE 329: literal_append(sql, ce.expression) 330: end 331: w = CASE_WHEN 332: t = CASE_THEN 333: ce.conditions.each do |c,r| 334: sql << w 335: literal_append(sql, c) 336: sql << t 337: literal_append(sql, r) 338: end 339: sql << CASE_ELSE 340: literal_append(sql, ce.default) 341: sql << CASE_END 342: end
SQL fragment for the complex expression.
# File lib/sequel/dataset/sql.rb, line 358 358: def complex_expression_sql_append(sql, op, args) 359: case op 360: when *IS_OPERATORS 361: r = args.at(1) 362: if r.nil? || supports_is_true? 363: raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r] 364: sql << PAREN_OPEN 365: literal_append(sql, args.at(0)) 366: sql << SPACE << op.to_s << SPACE 367: sql << val << PAREN_CLOSE 368: elsif op == :IS 369: complex_expression_sql_append(sql, "=""=", args) 370: else 371: complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)]) 372: end 373: when :IN, "NOT IN""NOT IN" 374: cols = args.at(0) 375: vals = args.at(1) 376: col_array = true if cols.is_a?(Array) 377: if vals.is_a?(Array) 378: val_array = true 379: empty_val_array = vals == [] 380: end 381: if empty_val_array 382: literal_append(sql, empty_array_value(op, cols)) 383: elsif col_array 384: if !supports_multiple_column_in? 385: if val_array 386: 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]})}) 387: literal_append(sql, op == :IN ? expr : ~expr) 388: else 389: old_vals = vals 390: vals = vals.naked if vals.is_a?(Sequel::Dataset) 391: vals = vals.to_a 392: val_cols = old_vals.columns 393: complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}]) 394: end 395: else 396: # If the columns and values are both arrays, use array_sql instead of 397: # literal so that if values is an array of two element arrays, it 398: # will be treated as a value list instead of a condition specifier. 399: sql << PAREN_OPEN 400: literal_append(sql, cols) 401: sql << SPACE << op.to_s << SPACE 402: if val_array 403: array_sql_append(sql, vals) 404: else 405: literal_append(sql, vals) 406: end 407: sql << PAREN_CLOSE 408: end 409: else 410: sql << PAREN_OPEN 411: literal_append(sql, cols) 412: sql << SPACE << op.to_s << SPACE 413: literal_append(sql, vals) 414: sql << PAREN_CLOSE 415: end 416: when :LIKE, 'NOT LIKE''NOT LIKE' 417: sql << PAREN_OPEN 418: literal_append(sql, args.at(0)) 419: sql << SPACE << op.to_s << SPACE 420: literal_append(sql, args.at(1)) 421: sql << ESCAPE 422: literal_append(sql, BACKSLASH) 423: sql << PAREN_CLOSE 424: when :ILIKE, 'NOT ILIKE''NOT ILIKE' 425: complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : "NOT LIKE""NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)}) 426: when *TWO_ARITY_OPERATORS 427: if REGEXP_OPERATORS.include?(op) && !supports_regexp? 428: raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}" 429: end 430: sql << PAREN_OPEN 431: literal_append(sql, args.at(0)) 432: sql << SPACE << op.to_s << SPACE 433: literal_append(sql, args.at(1)) 434: sql << PAREN_CLOSE 435: when *N_ARITY_OPERATORS 436: sql << PAREN_OPEN 437: c = false 438: op_str = " #{op} " 439: args.each do |a| 440: sql << op_str if c 441: literal_append(sql, a) 442: c ||= true 443: end 444: sql << PAREN_CLOSE 445: when :NOT 446: sql << NOT_SPACE 447: literal_append(sql, args.at(0)) 448: when :NOOP 449: literal_append(sql, args.at(0)) 450: when 'B~''B~' 451: sql << TILDE 452: literal_append(sql, args.at(0)) 453: when :extract 454: sql << EXTRACT << args.at(0).to_s << FROM 455: literal_append(sql, args.at(1)) 456: sql << PAREN_CLOSE 457: else 458: raise(InvalidOperation, "invalid operator #{op}") 459: end 460: end
SQL fragment specifying an emulated SQL function call. By default, assumes just the function name may need to be emulated, adapters should set an EMULATED_FUNCTION_MAP hash mapping emulated functions to native functions in their dataset class to setup the emulation.
# File lib/sequel/dataset/sql.rb, line 478 478: def emulated_function_sql_append(sql, f) 479: _function_sql_append(sql, native_function_name(f.f), f.args) 480: end
SQL fragment specifying a JOIN clause without ON or USING.
# File lib/sequel/dataset/sql.rb, line 488 488: def join_clause_sql_append(sql, jc) 489: table = jc.table 490: table_alias = jc.table_alias 491: table_alias = nil if table == table_alias 492: sql << SPACE << join_type_sql(jc.join_type) << SPACE 493: identifier_append(sql, table) 494: as_sql_append(sql, table_alias) if table_alias 495: end
SQL fragment for the ordered expression, used in the ORDER BY clause.
# File lib/sequel/dataset/sql.rb, line 520 520: def ordered_expression_sql_append(sql, oe) 521: literal_append(sql, oe.expression) 522: sql << (oe.descending ? DESC : ASC) 523: case oe.nulls 524: when :first 525: sql << NULLS_FIRST 526: when :last 527: sql << NULLS_LAST 528: end 529: end
SQL fragment for a literal string with placeholders
# File lib/sequel/dataset/sql.rb, line 532 532: def placeholder_literal_string_sql_append(sql, pls) 533: args = pls.args 534: str = pls.str 535: sql << PAREN_OPEN if pls.parens 536: if args.is_a?(Hash) 537: re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/ 538: loop do 539: previous, q, str = str.partition(re) 540: sql << previous 541: literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty? 542: break if str.empty? 543: end 544: elsif str.is_a?(Array) 545: len = args.length 546: str.each_with_index do |s, i| 547: sql << s 548: literal_append(sql, args[i]) unless i == len 549: end 550: unless str.length == args.length || str.length == args.length + 1 551: raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array" 552: end 553: else 554: i = -1 555: match_len = args.length - 1 556: loop do 557: previous, q, str = str.partition(QUESTION_MARK) 558: sql << previous 559: literal_append(sql, args.at(i+=1)) unless q.empty? 560: if str.empty? 561: unless i == match_len 562: raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder array" 563: end 564: break 565: end 566: end 567: end 568: sql << PAREN_CLOSE if pls.parens 569: 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 575 575: def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) 576: identifier_append(sql, table) 577: sql << DOT 578: identifier_append(sql, column) 579: 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 584 584: def quote_identifier_append(sql, name) 585: if name.is_a?(LiteralString) 586: sql << name 587: else 588: name = name.value if name.is_a?(SQL::Identifier) 589: name = input_identifier(name) 590: if quote_identifiers? 591: quoted_identifier_append(sql, name) 592: else 593: sql << name 594: end 595: end 596: end
Separates the schema from the table and returns a string with them quoted (if quoting identifiers)
# File lib/sequel/dataset/sql.rb, line 600 600: def quote_schema_table_append(sql, table) 601: schema, table = schema_and_table(table) 602: if schema 603: quote_identifier_append(sql, schema) 604: sql << DOT 605: end 606: quote_identifier_append(sql, table) 607: 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 612 612: def quoted_identifier_append(sql, name) 613: sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE 614: end
Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.
Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).
# File lib/sequel/dataset/sql.rb, line 623 623: def schema_and_table(table_name, sch=nil) 624: sch = sch.to_s if sch 625: case table_name 626: when Symbol 627: s, t, _ = split_symbol(table_name) 628: [s||sch, t] 629: when SQL::QualifiedIdentifier 630: [table_name.table.to_s, table_name.column.to_s] 631: when SQL::Identifier 632: [sch, table_name.value.to_s] 633: when String 634: [sch, table_name] 635: else 636: raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String' 637: end 638: end
Splits table_name into an array of strings.
ds.split_qualifiers(:s) # ['s'] ds.split_qualifiers(:t__s) # ['t', 's'] ds.split_qualifiers(Sequel.qualify(:d, :t__s)) # ['d', 't', 's'] ds.split_qualifiers(Sequel.qualify(:h__d, :t__s)) # ['h', 'd', 't', 's']
# File lib/sequel/dataset/sql.rb, line 646 646: def split_qualifiers(table_name, *args) 647: case table_name 648: when SQL::QualifiedIdentifier 649: split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil) 650: else 651: sch, table = schema_and_table(table_name, *args) 652: sch ? [sch, table] : [table] 653: end 654: end
SQL fragment for specifying subscripts (SQL array accesses)
# File lib/sequel/dataset/sql.rb, line 657 657: def subscript_sql_append(sql, s) 658: literal_append(sql, s.f) 659: sql << BRACKET_OPEN 660: if s.sub.length == 1 && (range = s.sub.first).is_a?(Range) 661: literal_append(sql, range.begin) 662: sql << COLON 663: e = range.end 664: e -= 1 if range.exclude_end? && e.is_a?(Integer) 665: literal_append(sql, e) 666: else 667: expression_list_append(sql, s.sub) 668: end 669: sql << BRACKET_CLOSE 670: end
The SQL fragment for the given window‘s options.
# File lib/sequel/dataset/sql.rb, line 673 673: def window_sql_append(sql, opts) 674: raise(Error, 'This dataset does not support window functions') unless supports_window_functions? 675: sql << PAREN_OPEN 676: window, part, order, frame = opts.values_at(:window, :partition, :order, :frame) 677: space = false 678: space_s = SPACE 679: if window 680: literal_append(sql, window) 681: space = true 682: end 683: if part 684: sql << space_s if space 685: sql << PARTITION_BY 686: expression_list_append(sql, Array(part)) 687: space = true 688: end 689: if order 690: sql << space_s if space 691: sql << ORDER_BY_NS 692: expression_list_append(sql, Array(order)) 693: space = true 694: end 695: case frame 696: when nil 697: # nothing 698: when :all 699: sql << space_s if space 700: sql << FRAME_ALL 701: when :rows 702: sql << space_s if space 703: sql << FRAME_ROWS 704: when String 705: sql << space_s if space 706: sql << frame 707: else 708: raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil" 709: end 710: sql << PAREN_CLOSE 711: end
These methods all return modified copies of the receiver.
EXTENSIONS | = | {} | Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension). | |
COLUMN_CHANGE_OPTS | = | [:select, :sql, :from, :join].freeze | The dataset options that require the removal of cached columns if changed. | |
NON_SQL_OPTIONS | = | [:server, :defaults, :overrides, :graph, :eager_graph, :graph_aliases] | Which options don‘t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table. | |
CONDITIONED_JOIN_TYPES | = | [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left] | 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. | |
UNCONDITIONED_JOIN_TYPES | = | [:natural, :natural_left, :natural_right, :natural_full, :cross] | 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. | |
JOIN_METHODS | = | (CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table] | All methods that return modified datasets with a joined table added. | |
QUERY_METHODS | = | (<<-METHS).split.map{|x| x.to_sym} + JOIN_METHODS add_graph_aliases and distinct except exclude exclude_having exclude_where filter for_update from from_self graph grep group group_and_count group_by having intersect invert limit lock_style naked or order order_append order_by order_more order_prepend paginate qualify query reverse reverse_order select select_all select_append select_group select_more server set_defaults set_graph_aliases set_overrides unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS ).split.map{|x| x.to_sym} + JOIN_METHODS | Methods that return modified datasets |
Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.
If mod is a module, this also registers a Database extension that will extend all of the database‘s datasets.
# File lib/sequel/dataset/query.rb, line 55 55: def self.register_extension(ext, mod=nil, &block) 56: if mod 57: raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block 58: if mod.is_a?(Module) 59: block = proc{|ds| ds.extend(mod)} 60: Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)} 61: else 62: block = mod 63: end 64: end 65: Sequel.synchronize{EXTENSIONS[ext] = block} 66: 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 77 77: def clone(opts = nil) 78: c = super() 79: if opts 80: c.instance_variable_set(:@opts, @opts.merge(opts)) 81: c.instance_variable_set(:@columns, nil) if @columns && !opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)} 82: else 83: c.instance_variable_set(:@opts, @opts.dup) 84: end 85: c 86: 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 97 97: def distinct(*args) 98: raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on? 99: clone(:distinct => args) 100: 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 119 119: def except(dataset, opts=OPTS) 120: raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except? 121: raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all? 122: compound_clone(:except, dataset, opts) 123: end
Performs the inverse of Dataset#where. 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 133 133: def exclude(*cond, &block) 134: _filter_or_exclude(true, :where, *cond, &block) 135: 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 141 141: def exclude_having(*cond, &block) 142: _filter_or_exclude(true, :having, *cond, &block) 143: 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. If a block is given, it is treated as a virtual row block, similar to where.
DB[:items].from # SQL: SELECT * DB[:items].from(:blah) # SQL: SELECT * FROM blah DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
# File lib/sequel/dataset/query.rb, line 176 176: def from(*source, &block) 177: virtual_row_columns(source, block) 178: table_alias_num = 0 179: ctes = nil 180: source.map! do |s| 181: case s 182: when Dataset 183: if hoist_cte?(s) 184: ctes ||= [] 185: ctes += s.opts[:with] 186: s = s.clone(:with=>nil) 187: end 188: SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1)) 189: when Symbol 190: sch, table, aliaz = split_symbol(s) 191: if aliaz 192: s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table) 193: SQL::AliasedExpression.new(s, aliaz.to_sym) 194: else 195: s 196: end 197: else 198: s 199: end 200: end 201: o = {:from=>source.empty? ? nil : source} 202: o[:with] = (opts[:with] || []) + ctes if ctes 203: o[:num_dataset_sources] = table_alias_num if table_alias_num > 0 204: clone(o) 205: 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 218 218: def from_self(opts=OPTS) 219: fs = {} 220: @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)} 221: clone(fs).from(opts[:alias] ? as(opts[:alias]) : self) 222: 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 255 255: def grep(columns, patterns, opts=OPTS) 256: if opts[:all_patterns] 257: conds = Array(patterns).map do |pat| 258: SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)}) 259: end 260: where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds)) 261: else 262: conds = Array(columns).map do |c| 263: SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)}) 264: end 265: where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds)) 266: end 267: 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 where.
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 276 276: def group(*columns, &block) 277: virtual_row_columns(columns, block) 278: clone(:group => (columns.compact.empty? ? nil : columns)) 279: 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 where.
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 307 307: def group_and_count(*columns, &block) 308: select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT) 309: end
Adds the appropriate CUBE syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 312 312: def group_cube 313: raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube? 314: clone(:group_options=>:cube) 315: end
Adds the appropriate ROLLUP syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 318 318: def group_rollup 319: raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup? 320: clone(:group_options=>:rollup) 321: end
Returns a copy of the dataset with the HAVING conditions changed. See where 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 327 327: def having(*cond, &block) 328: _filter(:having, *cond, &block) 329: 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 348 348: def intersect(dataset, opts=OPTS) 349: raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except? 350: raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all? 351: compound_clone(:intersect, dataset, opts) 352: end
Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.
DB[:items].where(:category => 'software').invert # SELECT * FROM items WHERE (category != 'software') DB[:items].where(:category => 'software', :id=>3).invert # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
# File lib/sequel/dataset/query.rb, line 362 362: def invert 363: having, where = @opts.values_at(:having, :where) 364: if having.nil? && where.nil? 365: where(false) 366: else 367: o = {} 368: o[:having] = SQL::BooleanExpression.invert(having) if having 369: o[:where] = SQL::BooleanExpression.invert(where) if where 370: clone(o) 371: end 372: end
Alias of inner_join
# File lib/sequel/dataset/query.rb, line 375 375: def join(*args, &block) 376: inner_join(*args, &block) 377: 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:
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| (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>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 433 433: def join_table(type, table, expr=nil, options=OPTS, &block) 434: if hoist_cte?(table) 435: s, ds = hoist_cte(table) 436: return s.join_table(type, ds, expr, options, &block) 437: end 438: 439: using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)} 440: if using_join && !supports_join_using? 441: h = {} 442: expr.each{|e| h[e] = e} 443: return join_table(type, table, h, options) 444: end 445: 446: table_alias = options[:table_alias] 447: last_alias = options[:implicit_qualifier] 448: qualify_type = options[:qualify] 449: 450: if table.is_a?(Dataset) 451: if table_alias.nil? 452: table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 453: table_alias = dataset_alias(table_alias_num) 454: end 455: table_name = table_alias 456: else 457: table, implicit_table_alias = split_alias(table) 458: table_alias ||= implicit_table_alias 459: table_name = table_alias || table 460: end 461: 462: join = if expr.nil? and !block 463: SQL::JoinClause.new(type, table, table_alias) 464: elsif using_join 465: raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block 466: SQL::JoinUsingClause.new(expr, type, table, table_alias) 467: else 468: last_alias ||= @opts[:last_joined_table] || first_source_alias 469: if Sequel.condition_specifier?(expr) 470: expr = expr.collect do |k, v| 471: qualify_type = default_join_table_qualification if qualify_type.nil? 472: case qualify_type 473: when false 474: nil # Do no qualification 475: when :deep 476: k = Sequel::Qualifier.new(self, table_name).transform(k) 477: v = Sequel::Qualifier.new(self, last_alias).transform(v) 478: else 479: k = qualified_column_name(k, table_name) if k.is_a?(Symbol) 480: v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) 481: end 482: [k,v] 483: end 484: expr = SQL::BooleanExpression.from_value_pairs(expr) 485: end 486: if block 487: expr2 = yield(table_name, last_alias, @opts[:join] || []) 488: expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 489: end 490: SQL::JoinOnClause.new(expr, type, table, table_alias) 491: end 492: 493: opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name} 494: opts[:num_dataset_sources] = table_alias_num if table_alias_num 495: clone(opts) 496: 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 515 515: def limit(l, o = (no_offset = true; nil)) 516: return from_self.limit(l, o) if @opts[:sql] 517: 518: if l.is_a?(Range) 519: o = l.first 520: l = l.last - l.first + (l.exclude_end? ? 0 : 1) 521: end 522: l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString) 523: if l.is_a?(Integer) 524: raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 525: end 526: opts = {:limit => l} 527: if o 528: o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString) 529: if o.is_a?(Integer) 530: raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 531: end 532: opts[:offset] = o 533: elsif !no_offset 534: opts[:offset] = nil 535: end 536: clone(opts) 537: end
Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.
A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).
DB[:items].lock_style('FOR SHARE NOWAIT') # SELECT * FROM items FOR SHARE NOWAIT
# File lib/sequel/dataset/query.rb, line 548 548: def lock_style(style) 549: clone(:lock => style) 550: 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 558 558: def naked 559: ds = clone 560: ds.row_proc = nil 561: ds 562: end
Adds an alternate filter to an existing filter using OR. If no filter exists an Error is raised.
DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
# File lib/sequel/dataset/query.rb, line 568 568: def or(*cond, &block) 569: cond = cond.first if cond.size == 1 570: v = @opts[:where] 571: if v.nil? || (cond.respond_to?(:empty?) && cond.empty? && !block) 572: clone 573: else 574: clone(:where => SQL::BooleanExpression.new(:OR, v, filter_expr(cond, &block))) 575: end 576: 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 where.
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(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b) DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC DB[:items].order(Sequel.asc(:name, :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 592 592: def order(*columns, &block) 593: virtual_row_columns(columns, block) 594: clone(:order => (columns.compact.empty?) ? nil : columns) 595: end
Alias of order_more, for naming consistency with order_prepend.
# File lib/sequel/dataset/query.rb, line 598 598: def order_append(*columns, &block) 599: order_more(*columns, &block) 600: 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 612 612: def order_more(*columns, &block) 613: columns = @opts[:order] + columns if @opts[:order] 614: order(*columns, &block) 615: 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 622 622: def order_prepend(*columns, &block) 623: ds = order(*columns, &block) 624: @opts[:order] ? ds.order_more(*@opts[:order]) : ds 625: end
Qualify to the given table, or first source if no table is given.
DB[:items].where(:id=>1).qualify # SELECT items.* FROM items WHERE (items.id = 1) DB[:items].where(:id=>1).qualify(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 634 634: def qualify(table=first_source) 635: o = @opts 636: return clone if o[:sql] 637: h = {} 638: (o.keys & QUALIFY_KEYS).each do |k| 639: h[k] = qualified_expression(o[k], table) 640: end 641: h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty? 642: clone(h) 643: 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 653 653: def returning(*values) 654: clone(:returning=>values) 655: 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].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
# File lib/sequel/dataset/query.rb, line 664 664: def reverse(*order, &block) 665: virtual_row_columns(order, block) 666: order(*invert_order(order.empty? ? @opts[:order] : order)) 667: 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 where.
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 681 681: def select(*columns, &block) 682: virtual_row_columns(columns, block) 683: clone(:select => columns) 684: 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 693 693: def select_all(*tables) 694: if tables.empty? 695: clone(:select => nil) 696: else 697: select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)}) 698: end 699: 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 708 708: def select_append(*columns, &block) 709: cur_sel = @opts[:select] 710: if !cur_sel || cur_sel.empty? 711: unless supports_select_all_and_column? 712: return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block) 713: end 714: cur_sel = [WILDCARD] 715: end 716: select(*(cur_sel + columns), &block) 717: 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 where.
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 728 728: def select_group(*columns, &block) 729: virtual_row_columns(columns, block) 730: select(*columns).group(*columns.map{|c| unaliased_identifier(c)}) 731: end
Alias for select_append.
# File lib/sequel/dataset/query.rb, line 734 734: def select_more(*columns, &block) 735: select_append(*columns, &block) 736: 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 747 747: def server(servr) 748: clone(:server=>servr) 749: 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].where(:a=>1).unbind ds # SELECT * FROM items WHERE (a = $a) bv # {:a => 1} ds.call(:select, bv)
# File lib/sequel/dataset/query.rb, line 761 761: def unbind 762: u = Unbinder.new 763: ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join])) 764: [ds, u.binds] 765: 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 799 799: def union(dataset, opts=OPTS) 800: compound_clone(:union, dataset, opts) 801: end
Returns a copy of the dataset with the given WHERE conditions imposed upon it.
Accepts the following argument types:
where also accepts 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].where(:id => 3) # SELECT * FROM items WHERE (id = 3) DB[:items].where('price < ?', 100) # SELECT * FROM items WHERE price < 100 DB[:items].where([[:id, [1,2,3]], [:id, 0..10]]) # SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10))) DB[:items].where('price < 100') # SELECT * FROM items WHERE price < 100 DB[:items].where(:active) # SELECT * FROM items WHERE :active DB[:items].where{price < 100} # SELECT * FROM items WHERE (price < 100)
Multiple where calls can be chained for scoping:
software = dataset.where(:category => 'software').where{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 867 867: def where(*cond, &block) 868: _filter(:where, *cond, &block) 869: 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].where(:name.like('A%'))) # WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 879 879: def with(name, dataset, opts=OPTS) 880: raise(Error, 'This datatset does not support common table expressions') unless supports_cte? 881: if hoist_cte?(dataset) 882: s, ds = hoist_cte(dataset) 883: s.with(name, ds, opts) 884: else 885: clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)]) 886: end 887: 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].with_recursive(:t, DB[:i1].select(:id, :parent_id).where(:parent_id=>nil), DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :i1__parent_id), :args=>[:id, :parent_id]) # WITH RECURSIVE "t"("id", "parent_id") AS ( # SELECT "id", "parent_id" FROM "i1" WHERE ("parent_id" IS NULL) # UNION ALL # SELECT "i1"."id", "i1"."parent_id" FROM "i1" INNER JOIN "t" ON ("t"."id" = "i1"."parent_id") # ) SELECT * FROM "t"
# File lib/sequel/dataset/query.rb, line 905 905: def with_recursive(name, nonrecursive, recursive, opts=OPTS) 906: raise(Error, 'This datatset does not support common table expressions') unless supports_cte? 907: if hoist_cte?(nonrecursive) 908: s, ds = hoist_cte(nonrecursive) 909: s.with_recursive(name, ds, recursive, opts) 910: elsif hoist_cte?(recursive) 911: s, ds = hoist_cte(recursive) 912: s.with_recursive(name, nonrecursive, ds, opts) 913: else 914: clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]) 915: end 916: 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 930 930: def with_sql(sql, *args) 931: if sql.is_a?(Symbol) 932: sql = send(sql, *args) 933: else 934: sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty? 935: end 936: clone(:sql=>sql) 937: end
Add the dataset to the list of compounds
# File lib/sequel/dataset/query.rb, line 942 942: def compound_clone(type, dataset, opts) 943: if hoist_cte?(dataset) 944: s, ds = hoist_cte(dataset) 945: return s.compound_clone(type, ds, opts) 946: end 947: ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]]) 948: opts[:from_self] == false ? ds : ds.from_self(opts) 949: end
Return true if the dataset has a non-nil value for any key in opts.
# File lib/sequel/dataset/query.rb, line 952 952: def options_overlap(opts) 953: !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty? 954: end
Whether this dataset is a simple SELECT * FROM table.
# File lib/sequel/dataset/query.rb, line 957 957: def simple_select_all? 958: o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)} 959: o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression)) 960: end
These methods all execute the dataset‘s SQL on the database. They don‘t return modified datasets, so if used in a method chain they should be the last method called.
ACTION_METHODS | = | (<<-METHS).split.map{|x| x.to_sym} << [] []= all avg count columns columns! delete each empty? fetch_rows first first! get import insert insert_multiple interval last map max min multi_insert paged_each range select_hash select_hash_groups select_map select_order_map set single_record single_value sum to_csv to_hash to_hash_groups truncate update METHS ).split.map{|x| x.to_sym} | Action methods defined by Sequel that execute code on the database. | |
DatasetClass | = | self | ||
DatasetClass | = | self | ||
JAVA_SQL_TIMESTAMP | = | Java::JavaSQL::Timestamp | Cache Java class constants to speed up lookups | |
JAVA_SQL_TIME | = | Java::JavaSQL::Time | ||
JAVA_SQL_DATE | = | Java::JavaSQL::Date | ||
JAVA_SQL_BLOB | = | Java::JavaSQL::Blob | ||
JAVA_SQL_CLOB | = | Java::JavaSQL::Clob | ||
JAVA_BUFFERED_READER | = | Java::JavaIo::BufferedReader | ||
JAVA_BIG_DECIMAL | = | Java::JavaMath::BigDecimal | ||
JAVA_BYTE_ARRAY | = | Java::byte[] | ||
JAVA_UUID | = | Java::JavaUtil::UUID | ||
JAVA_HASH_MAP | = | Java::JavaUtil::HashMap | ||
TYPE_TRANSLATOR_INSTANCE | = | tt = TYPE_TRANSLATOR.new | ||
DECIMAL_METHOD | = | tt.method(:decimal) | Cache type translator methods so that duplicate Method objects are not created. | |
TIME_METHOD | = | tt.method(:time) | ||
DATE_METHOD | = | tt.method(:date) | ||
BUFFERED_READER_METHOD | = | tt.method(:buffered_reader) | ||
BYTE_ARRAY_METHOD | = | tt.method(:byte_array) | ||
BLOB_METHOD | = | tt.method(:blob) | ||
CLOB_METHOD | = | tt.method(:clob) | ||
UUID_METHOD | = | tt.method(:uuid) | ||
HASH_MAP_METHOD | = | tt.method(:hash_map) | ||
DatasetClass | = | self | ||
DatasetClass | = | self | ||
DatasetClass | = | self | ||
PREPARED_ARG_PLACEHOLDER | = | ':'.freeze | ||
OPTS | = | Sequel::OPTS |
convert_types | [RW] | Whether to convert some Java types to ruby types when retrieving rows. Uses the database‘s setting by default, can be set to false to roughly double performance when fetching rows. |
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 24 24: def <<(arg) 25: insert(arg) 26: self 27: 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 33 33: def [](*conditions) 34: raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0 35: first(*conditions) 36: 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 46 46: def all(&block) 47: a = [] 48: each{|r| a << r} 49: post_load(a) 50: a.each(&block) if block 51: a 52: end
Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1 # => 3 DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 61 61: def avg(column=Sequel.virtual_row(&Proc.new)) 62: aggregate_dataset.get{avg(column).as(:avg)} 63: 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 74 74: def columns 75: return @columns if @columns 76: ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil) 77: ds.each{break} 78: @columns = ds.instance_variable_get(:@columns) 79: @columns || [] 80: end
Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.
DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1 # => 3 DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1 # => 2 DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 103 103: def count(arg=(no_arg=true), &block) 104: if no_arg 105: if block 106: arg = Sequel.virtual_row(&block) 107: aggregate_dataset.get{count(arg).as(count)} 108: else 109: aggregate_dataset.get{count(:*){}.as(count)}.to_i 110: end 111: elsif block 112: raise Error, 'cannot provide both argument and block to Dataset#count' 113: else 114: aggregate_dataset.get{count(arg).as(count)} 115: end 116: 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 123 123: def delete(&block) 124: sql = delete_sql 125: if uses_returning?(:delete) 126: returning_fetch_rows(sql, &block) 127: else 128: execute_dui(sql) 129: end 130: 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 141 141: def each 142: if row_proc = @row_proc 143: fetch_rows(select_sql){|r| yield row_proc.call(r)} 144: else 145: fetch_rows(select_sql){|r| yield r} 146: end 147: self 148: 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 154 154: def empty? 155: get(Sequel::SQL::AliasedExpression.new(1, :one)).nil? 156: end
Yield a hash for each row in the dataset.
# File lib/sequel/adapters/sqlite.rb, line 355 355: def fetch_rows(sql) 356: execute(sql) do |result| 357: i = -1 358: cps = db.conversion_procs 359: type_procs = result.types.map{|t| cps[base_type_name(t)]} 360: cols = result.columns.map{|c| i+=1; [output_identifier(c), i, type_procs[i]]} 361: @columns = cols.map{|c| c.first} 362: result.each do |values| 363: row = {} 364: cols.each do |name,id,type_proc| 365: v = values[id] 366: if type_proc && v 367: v = type_proc.call(v) 368: end 369: row[name] = v 370: end 371: yield row 372: end 373: end 374: end
Execute the SQL on the database and yield the rows as hashes with symbol keys.
# File lib/sequel/adapters/do.rb, line 155 155: def fetch_rows(sql) 156: execute(sql) do |reader| 157: cols = @columns = reader.fields.map{|f| output_identifier(f)} 158: while(reader.next!) do 159: h = {} 160: cols.zip(reader.values).each{|k, v| h[k] = v} 161: yield h 162: end 163: end 164: self 165: 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 && cast_tinyint_integer?(f) ? 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
Set the columns and yield the hashes to the block.
# File lib/sequel/adapters/swift.rb, line 132 132: def fetch_rows(sql) 133: execute(sql) do |res| 134: col_map = {} 135: @columns = res.fields.map do |c| 136: col_map[c] = output_identifier(c) 137: end 138: res.each do |r| 139: h = {} 140: r.each do |k, v| 141: h[col_map[k]] = v.is_a?(StringIO) ? SQL::Blob.new(v.read) : v 142: end 143: yield h 144: end 145: end 146: self 147: 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.
If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).
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 193 193: def first(*args, &block) 194: ds = block ? filter(&block) : self 195: 196: if args.empty? 197: ds.single_record 198: else 199: args = (args.size == 1) ? args.first : args 200: if args.is_a?(Integer) 201: ds.limit(args).all 202: else 203: ds.filter(args).single_record 204: end 205: end 206: end
Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.
# File lib/sequel/dataset/actions.rb, line 210 210: def first!(*args, &block) 211: first(*args, &block) || raise(Sequel::NoMatchingRow) 212: 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) AS v FROM table LIMIT 1 # => 6
You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:
DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1 # => [3, 'foo'] DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1 # => [6, 'foo']
# File lib/sequel/dataset/actions.rb, line 232 232: def get(column=(no_arg=true; nil), &block) 233: ds = naked 234: if block 235: raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg 236: ds = ds.select(&block) 237: column = ds.opts[:select] 238: column = nil if column.is_a?(Array) && column.length < 2 239: else 240: ds = if column.is_a?(Array) 241: ds.select(*column) 242: else 243: ds.select(auto_alias_expression(column)) 244: end 245: end 246: 247: if column.is_a?(Array) 248: if r = ds.single_record 249: r.values_at(*hash_key_symbols(column)) 250: end 251: else 252: ds.single_value 253: end 254: 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
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 279 279: def import(columns, values, opts=OPTS) 280: return @db.transaction{insert(columns, values)} if values.is_a?(Dataset) 281: 282: return if values.empty? 283: raise(Error, IMPORT_ERROR_MSG) if columns.empty? 284: ds = opts[:server] ? server(opts[:server]) : self 285: 286: if slice_size = opts[:commit_every] || opts[:slice] 287: offset = 0 288: rows = [] 289: while offset < values.length 290: rows << ds._import(columns, values[offset, slice_size], opts) 291: offset += slice_size 292: end 293: rows.flatten 294: else 295: ds._import(columns, values, opts) 296: end 297: 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 : | Uses DEFAULT VALUES |
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 334 334: def insert(*values, &block) 335: sql = insert_sql(*values) 336: if uses_returning?(:insert) 337: returning_fetch_rows(sql, &block) 338: else 339: execute_insert(sql) 340: end 341: end
Returns the interval between minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1 # => 6 DB[:table].interval{function(column)} # SELECT (max(function(column)) - min(function(column))) FROM table LIMIT 1 # => 7
# File lib/sequel/dataset/actions.rb, line 350 350: def interval(column=Sequel.virtual_row(&Proc.new)) 351: aggregate_dataset.get{(max(column) - min(column)).as(:interval)} 352: end
Reverses the order and then runs first 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(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2 # => [{:id=>1}, {:id=>2}]
# File lib/sequel/dataset/actions.rb, line 364 364: def last(*args, &block) 365: raise(Error, 'No order specified') unless @opts[:order] 366: reverse.first(*args, &block) 367: 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 383 383: def map(column=nil, &block) 384: if column 385: raise(Error, ARG_BLOCK_ERROR_MSG) if block 386: return naked.map(column) if row_proc 387: if column.is_a?(Array) 388: super(){|r| r.values_at(*column)} 389: else 390: super(){|r| r[column]} 391: end 392: else 393: super(&block) 394: end 395: end
Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1 # => 10 DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1 # => 7
# File lib/sequel/dataset/actions.rb, line 404 404: def max(column=Sequel.virtual_row(&Proc.new)) 405: aggregate_dataset.get{max(column).as(:max)} 406: end
Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1 # => 1 DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1 # => 0
# File lib/sequel/dataset/actions.rb, line 415 415: def min(column=Sequel.virtual_row(&Proc.new)) 416: aggregate_dataset.get{min(column).as(:min)} 417: 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 import.
# File lib/sequel/dataset/actions.rb, line 431 431: def multi_insert(hashes, opts=OPTS) 432: return if hashes.empty? 433: columns = hashes.first.keys 434: import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts) 435: end
Yields each row in the dataset, but interally uses multiple queries as needed with limit and offset to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.
Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to make sure that all rows in the dataset are yielded and none are yielded twice, the dataset must have an unambiguous order. Sequel requires that datasets using this method have an order, but it cannot ensure that the order is unambiguous.
Options:
:rows_per_fetch : | The number of rows to fetch per query. Defaults to 1000. |
# File lib/sequel/dataset/actions.rb, line 450 450: def paged_each(opts=OPTS) 451: unless @opts[:order] 452: raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered" 453: end 454: 455: total_limit = @opts[:limit] 456: offset = @opts[:offset] || 0 457: 458: if server = @opts[:server] 459: opts = opts.merge(:server=>server) 460: end 461: 462: rows_per_fetch = opts[:rows_per_fetch] || 1000 463: num_rows_yielded = rows_per_fetch 464: total_rows = 0 465: 466: db.transaction(opts) do 467: while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit) 468: if total_limit && total_rows + rows_per_fetch > total_limit 469: rows_per_fetch = total_limit - total_rows 470: end 471: 472: num_rows_yielded = 0 473: limit(rows_per_fetch, offset).each do |row| 474: num_rows_yielded += 1 475: total_rows += 1 if total_limit 476: yield row 477: end 478: 479: offset += rows_per_fetch 480: end 481: end 482: 483: self 484: end
Create a named prepared statement that is stored in the database (and connection) for reuse.
# File lib/sequel/adapters/jdbc.rb, line 677 677: def prepare(type, name=nil, *values) 678: ps = to_prepared_statement(type, values) 679: ps.extend(PreparedStatementMethods) 680: if name 681: ps.prepared_statement_name = name 682: db.set_prepared_statement(name, ps) 683: end 684: ps 685: 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/sqlite.rb, line 379 379: def prepare(type, name=nil, *values) 380: ps = to_prepared_statement(type, values) 381: ps.extend(PreparedStatementMethods) 382: if name 383: ps.prepared_statement_name = name 384: db.set_prepared_statement(name, ps) 385: end 386: ps 387: end
Returns a Range instance made from the minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1 # => 1..10 DB[:table].interval{function(column)} # SELECT max(function(column)) AS v1, min(function(column)) AS v2 FROM table LIMIT 1 # => 0..7
# File lib/sequel/dataset/actions.rb, line 493 493: def range(column=Sequel.virtual_row(&Proc.new)) 494: if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first 495: (r[:v1]..r[:v2]) 496: end 497: 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 as method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 514 514: def select_hash(key_column, value_column) 515: _select_hash(:to_hash, key_column, value_column) 516: 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 as method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 533 533: def select_hash_groups(key_column, value_column) 534: _select_hash(:to_hash_groups, key_column, value_column) 535: 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 as method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 557 557: def select_map(column=nil, &block) 558: _select_map(column, false, &block) 559: 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 as method on the expression and providing an alias.
# File lib/sequel/dataset/actions.rb, line 577 577: def select_order_map(column=nil, &block) 578: _select_map(column, true, &block) 579: 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
Returns the sum for the given column/expression. Uses a virtual row block if no column is given.
DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1 # => 55 DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1 # => 10
# File lib/sequel/dataset/actions.rb, line 605 605: def sum(column=Sequel.virtual_row(&Proc.new)) 606: aggregate_dataset.get{sum(column).as(:sum)} 607: 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 628 628: def to_hash(key_column, value_column = nil) 629: h = {} 630: if value_column 631: return naked.to_hash(key_column, value_column) if row_proc 632: if value_column.is_a?(Array) 633: if key_column.is_a?(Array) 634: each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)} 635: else 636: each{|r| h[r[key_column]] = r.values_at(*value_column)} 637: end 638: else 639: if key_column.is_a?(Array) 640: each{|r| h[r.values_at(*key_column)] = r[value_column]} 641: else 642: each{|r| h[r[key_column]] = r[value_column]} 643: end 644: end 645: elsif key_column.is_a?(Array) 646: each{|r| h[r.values_at(*key_column)] = r} 647: else 648: each{|r| h[r[key_column]] = r} 649: end 650: h 651: 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 671 671: def to_hash_groups(key_column, value_column = nil) 672: h = {} 673: if value_column 674: return naked.to_hash_groups(key_column, value_column) if row_proc 675: if value_column.is_a?(Array) 676: if key_column.is_a?(Array) 677: each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)} 678: else 679: each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)} 680: end 681: else 682: if key_column.is_a?(Array) 683: each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]} 684: else 685: each{|r| (h[r[key_column]] ||= []) << r[value_column]} 686: end 687: end 688: elsif key_column.is_a?(Array) 689: each{|r| (h[r.values_at(*key_column)] ||= []) << r} 690: else 691: each{|r| (h[r[key_column]] ||= []) << r} 692: end 693: h 694: end
Truncates the dataset. Returns nil.
DB[:table].truncate # TRUNCATE table # => nil
# File lib/sequel/dataset/actions.rb, line 700 700: def truncate 701: execute_ddl(truncate_sql) 702: 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 714 714: def update(values=OPTS, &block) 715: sql = update_sql(values) 716: if uses_returning?(:update) 717: returning_fetch_rows(sql, &block) 718: else 719: execute_dui(sql) 720: end 721: 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 726 726: def with_sql_delete(sql) 727: execute_dui(sql) 728: end
Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.
# File lib/sequel/dataset/actions.rb, line 735 735: def _import(columns, values, opts) 736: trans_opts = opts.merge(:server=>@opts[:server]) 737: if opts[:return] == :primary_key 738: @db.transaction(trans_opts){values.map{|v| insert(columns, v)}} 739: else 740: stmts = multi_insert_sql(columns, values) 741: @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}} 742: end 743: end
Return an array of arrays of values given by the symbols in ret_cols.
# File lib/sequel/dataset/actions.rb, line 746 746: def _select_map_multiple(ret_cols) 747: map{|r| r.values_at(*ret_cols)} 748: end
These methods all return booleans, with most describing whether or not the dataset supports a feature.