Class: Sequel::Dataset
- Extended by:
- Metaprogramming
- Includes:
- Enumerable, Metaprogramming
- Defined in:
- lib/sequel/dataset.rb,
lib/sequel/dataset/sql.rb,
lib/sequel/dataset/graph.rb,
lib/sequel/extensions/query.rb,
lib/sequel/dataset/convenience.rb,
lib/sequel/extensions/pagination.rb,
lib/sequel/extensions/pretty_table.rb,
lib/sequel/dataset/prepared_statements.rb,
lib/sequel/adapters/utils/stored_procedures.rb
Overview
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.
Methods added via metaprogramming
Some methods are added via metaprogramming:
-
! methods - These methods are the same as their non-! counterparts, but they modify the receiver instead of returning a modified copy of the dataset.
-
inner_join, full_outer_join, right_outer_join, left_outer_join - This methods are shortcuts to join_table with the join type already specified.
Direct Known Subclasses
ADO::Dataset, Amalgalite::Dataset, Sequel::DB2::Dataset, Sequel::DBI::Dataset, Sequel::DataObjects::Dataset, Firebird::Dataset, Informix::Dataset, JDBC::Dataset, MySQL::Dataset, ODBC::Dataset, OpenBase::Dataset, Oracle::Dataset, Postgres::Dataset, SQLite::Dataset
Defined Under Namespace
Modules: ArgumentMapper, Pagination, PreparedStatementMethods, QueryBlockCopy, StoredProcedureMethods, StoredProcedures, UnnumberedArgumentMapper
Constant Summary collapse
- COLUMN_CHANGE_OPTS =
The dataset options that require the removal of cached columns if changed.
[:select, :sql, :from, :join].freeze
- MUTATION_METHODS =
All methods that should have a ! method added that modifies the receiver.
%w'add_graph_aliases and distinct exclude exists filter from from_self full_outer_join graph group group_and_count group_by having inner_join intersect invert join left_outer_join limit naked or order order_by order_more paginate qualify query reject reverse reverse_order right_outer_join select select_all select_more set_defaults set_graph_aliases set_overrides sort sort_by unfiltered ungraphed union unordered where with with_sql'.collect{|x| x.to_sym}
- NOTIMPL_MSG =
"This method must be overridden in Sequel adapters".freeze
- WITH_SUPPORTED =
'with'.freeze
- AND_SEPARATOR =
" AND ".freeze
- BOOL_FALSE =
"'f'".freeze
- BOOL_TRUE =
"'t'".freeze
- COLUMN_REF_RE1 =
/\A([\w ]+)__([\w ]+)___([\w ]+)\z/.freeze
- COLUMN_REF_RE2 =
/\A([\w ]+)___([\w ]+)\z/.freeze
- COLUMN_REF_RE3 =
/\A([\w ]+)__([\w ]+)\z/.freeze
- COUNT_FROM_SELF_OPTS =
[:distinct, :group, :sql, :limit, :compounds]
- DATASET_ALIAS_BASE_NAME =
't'.freeze
- INSERT_SQL_BASE =
"INSERT INTO ".freeze
- IS_LITERALS =
{nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze
- IS_OPERATORS =
::Sequel::SQL::ComplexExpression::IS_OPERATORS
- N_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
- NULL =
"NULL".freeze
- QUALIFY_KEYS =
[:select, :where, :having, :order, :group]
- QUESTION_MARK =
'?'.freeze
- STOCK_COUNT_OPTS =
{:select => [SQL::AliasedExpression.new(LiteralString.new("COUNT(*)").freeze, :count)], :order => nil}.freeze
- SELECT_CLAUSE_ORDER =
%w'with distinct columns from join where group having compounds order limit'.freeze
- TWO_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
- WILDCARD =
'*'.freeze
- SQL_WITH =
"WITH ".freeze
- COMMA_SEPARATOR =
', '.freeze
- COUNT_OF_ALL_AS_COUNT =
SQL::Function.new(:count, LiteralString.new('*'.freeze)).as(:count)
- ARRAY_ACCESS_ERROR_MSG =
'You cannot call Dataset#[] with an integer or with no arguments.'.freeze
- MAP_ERROR_MSG =
'Using Dataset#map with an argument and a block is not allowed'.freeze
- GET_ERROR_MSG =
'must provide argument or block to Dataset#get, not both'.freeze
- IMPORT_ERROR_MSG =
'Using Sequel::Dataset#import an empty column array is not allowed'.freeze
- PREPARED_ARG_PLACEHOLDER =
LiteralString.new('?').freeze
Instance Attribute Summary collapse
-
#db ⇒ Object
The database that corresponds to this dataset.
-
#identifier_input_method ⇒ Object
Set the method to call on identifiers going into the database for this dataset.
-
#identifier_output_method ⇒ Object
Set the method to call on identifiers coming the database for this dataset.
-
#opts ⇒ Object
The hash of options for this dataset, keys are symbols.
-
#quote_identifiers ⇒ Object
writeonly
Whether to quote identifiers for this dataset.
-
#row_proc ⇒ Object
The row_proc for this database, should be a Proc that takes a single hash argument and returns the object you want each to return.
Class Method Summary collapse
-
.def_mutation_method(*meths) ⇒ Object
Setup mutation (e.g. filter!) methods.
Instance Method Summary collapse
-
#<<(*args) ⇒ Object
Alias for insert, but not aliased directly so subclasses don’t have to override both methods.
-
#[](*conditions) ⇒ Object
Returns the first record matching the conditions.
-
#[]=(conditions, values) ⇒ Object
Update all records matching the conditions with the values specified.
-
#add_graph_aliases(graph_aliases) ⇒ Object
Adds the given graph aliases to the list of graph aliases to use, unlike #set_graph_aliases, which replaces the list.
-
#aliased_expression_sql(ae) ⇒ Object
SQL fragment for the aliased expression.
-
#all(&block) ⇒ Object
Returns an array with all records in the dataset.
-
#and(*cond, &block) ⇒ Object
Adds an further filter to an existing filter using AND.
-
#array_sql(a) ⇒ Object
SQL fragment for the SQL array.
-
#as(aliaz) ⇒ Object
Return the dataset as an aliased expression with the given alias.
-
#avg(column) ⇒ Object
Returns the average value for the given column.
-
#call(type, bind_variables = {}, values = nil) ⇒ Object
For the given type (:select, :insert, :update, or :delete), run the sql with the bind variables specified in the hash.
-
#case_expression_sql(ce) ⇒ Object
SQL fragment for specifying given CaseExpression.
-
#cast_sql(expr, type) ⇒ Object
SQL fragment for the SQL CAST expression.
-
#clone(opts = {}) ⇒ Object
Returns a new clone of the dataset with with the given options merged.
-
#column_all_sql(ca) ⇒ Object
SQL fragment for specifying all columns in a given table.
-
#columns ⇒ Object
Returns the columns in the result set in order.
-
#columns! ⇒ Object
Remove the cached list of columns and do a SELECT query to find the columns.
-
#complex_expression_sql(op, args) ⇒ Object
SQL fragment for complex expressions.
-
#count ⇒ Object
Returns the number of records in the dataset.
-
#def_mutation_method(*meths) ⇒ Object
Add a mutation method to this dataset instance.
-
#delete ⇒ Object
Deletes the records in the dataset.
-
#delete_sql ⇒ Object
Formats a DELETE statement using the given options and dataset options.
-
#distinct(*args) ⇒ Object
Returns a copy of the dataset with the SQL DISTINCT clause.
-
#each(&block) ⇒ Object
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
-
#each_page(page_size, &block) ⇒ Object
Yields a paginated dataset for each page and returns the receiver.
-
#empty? ⇒ Boolean
Returns true if no records exist in the dataset, false otherwise.
-
#except(dataset, opts = {}) ⇒ Object
Adds an EXCEPT clause using a second dataset object.
-
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#filter.
-
#exists ⇒ Object
Returns an EXISTS clause for the dataset as a LiteralString.
-
#fetch_rows(sql, &block) ⇒ Object
Executes a select query and fetches records, passing each record to the supplied block.
-
#filter(*cond, &block) ⇒ Object
Returns a copy of the dataset with the given conditions imposed upon it.
-
#first(*args, &block) ⇒ Object
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit.
-
#first_source_alias ⇒ Object
(also: #first_source)
The first source (primary table) for this dataset.
-
#from(*source) ⇒ Object
Returns a copy of the dataset with the source changed.
-
#from_self ⇒ Object
Returns a dataset selecting from the current dataset.
-
#function_sql(f) ⇒ Object
SQL fragment specifying an SQL function call.
-
#get(column = nil, &block) ⇒ Object
Return the column value for the first matching record in the dataset.
-
#graph(dataset, join_conditions = nil, options = {}, &block) ⇒ Object
Allows you to join multiple datasets/tables and have the result set split into component tables.
-
#grep(cols, terms) ⇒ Object
Pattern match any of the columns to any of the terms.
-
#group(*columns) ⇒ Object
(also: #group_by)
Returns a copy of the dataset with the results grouped by the value of the given columns.
-
#group_and_count(*columns) ⇒ Object
Returns a dataset grouped by the given column with count by group, order by the count of records.
-
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the HAVING conditions changed.
-
#import(columns, values, opts = {}) ⇒ Object
Inserts multiple records into the associated table.
-
#initialize(db, opts = nil) ⇒ Dataset
constructor
Constructs a new Dataset instance with an associated database and options.
-
#insert(*values) ⇒ Object
Inserts values into the associated table.
-
#insert_multiple(array, &block) ⇒ Object
Inserts multiple values.
-
#insert_sql(*values) ⇒ Object
Formats an INSERT statement using the given values.
-
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
-
#intersect(dataset, opts = {}) ⇒ Object
Adds an INTERSECT clause using a second dataset object.
-
#interval(column) ⇒ Object
Returns the interval between minimum and maximum values for the given column.
-
#invert ⇒ Object
Inverts the current filter.
-
#join_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
-
#join_on_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
-
#join_table(type, table, expr = nil, options = {}, &block) ⇒ Object
Returns a joined dataset.
-
#join_using_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
-
#last(*args, &block) ⇒ Object
Reverses the order and then runs first.
-
#limit(l, o = nil) ⇒ Object
If given an integer, the dataset will contain only the first l results.
-
#literal(v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
-
#map(column = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable.
-
#max(column) ⇒ Object
Returns the maximum value for the given column.
-
#min(column) ⇒ Object
Returns the minimum value for the given column.
-
#multi_insert(hashes, opts = {}) ⇒ Object
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:.
-
#multi_insert_sql(columns, values) ⇒ Object
Returns an array of insert statements for inserting multiple records.
-
#naked ⇒ Object
Returns a naked dataset clone - i.e.
-
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR.
-
#order(*columns, &block) ⇒ Object
(also: #order_by)
Returns a copy of the dataset with the order changed.
-
#order_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the existing order.
-
#ordered_expression_sql(oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
-
#paginate(page_no, page_size, record_count = nil) ⇒ Object
Returns a paginated dataset.
-
#placeholder_literal_string_sql(pls) ⇒ Object
SQL fragment for a literal string with placeholders.
-
#prepare(type, name = nil, values = nil) ⇒ Object
Prepare an SQL statement for later execution.
-
#print(*cols) ⇒ Object
Pretty prints the records in the dataset as plain-text table.
-
#qualified_identifier_sql(qcr) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
-
#qualify(table = first_source) ⇒ Object
Qualify to the given table, or first source if not table is given.
-
#qualify_to(table) ⇒ Object
Return a copy of the dataset with unqualified identifiers in the SELECT, WHERE, GROUP, HAVING, and ORDER clauses qualified by the given table.
-
#qualify_to_first_source ⇒ Object
Qualify the dataset to its current first source.
-
#query(&block) ⇒ Object
Translates a query block into a dataset.
-
#quote_identifier(name) ⇒ Object
Adds quoting to identifiers (columns and tables).
-
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
-
#quote_schema_table(table) ⇒ Object
Separates the schema from the table and returns a string with them quoted (if quoting identifiers).
-
#quoted_identifier(name) ⇒ Object
This method quotes the given name with the SQL standard double quote.
-
#range(column) ⇒ Object
Returns a Range object made from the minimum and maximum values for the given column.
-
#requires_sql_standard_datetimes? ⇒ Boolean
Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format..
-
#reverse_order(*order) ⇒ Object
(also: #reverse)
Returns a copy of the dataset with the order reversed.
-
#schema_and_table(table_name) ⇒ Object
Split the schema information from the table.
-
#select(*columns, &block) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns.
-
#select_all ⇒ Object
Returns a copy of the dataset selecting the wildcard.
-
#select_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns.
-
#select_sql ⇒ Object
Formats a SELECT statement.
-
#server(servr) ⇒ Object
Set the server for this dataset to use.
-
#set(*args) ⇒ Object
Alias for set, but not aliased directly so subclasses don’t have to override both methods.
-
#set_defaults(hash) ⇒ Object
Set the default values for insert and update statements.
-
#set_graph_aliases(graph_aliases) ⇒ Object
This allows you to manually specify the graph aliases to use when using graph.
-
#set_overrides(hash) ⇒ Object
Set values that override hash arguments given to insert and update statements.
-
#single_record ⇒ Object
Returns the first record in the dataset.
-
#single_value ⇒ Object
Returns the first value of the first record in the dataset.
-
#sql ⇒ Object
Same as select_sql, not aliased directly to make subclassing simpler.
-
#subscript_sql(s) ⇒ Object
SQL fragment for specifying subscripts (SQL arrays).
-
#sum(column) ⇒ Object
Returns the sum for the given column.
-
#supports_cte? ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause).
-
#supports_distinct_on? ⇒ Boolean
Whether the dataset supports the DISTINCT ON clause, true by default.
-
#supports_intersect_except? ⇒ Boolean
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
-
#supports_intersect_except_all? ⇒ Boolean
Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.
-
#supports_is_true? ⇒ Boolean
Whether the dataset supports the IS TRUE syntax.
-
#supports_window_functions? ⇒ Boolean
Whether the dataset supports window functions.
-
#to_csv(include_column_titles = true) ⇒ Object
Returns a string in CSV format containing the dataset records.
-
#to_hash(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and another used as value.
-
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
-
#ungraphed ⇒ Object
Remove the splitting of results into subhashes.
-
#union(dataset, opts = {}) ⇒ Object
Adds a UNION clause using a second dataset object.
-
#unordered ⇒ Object
Returns a copy of the dataset with no order.
-
#update(values = {}) ⇒ Object
Updates values for the dataset.
-
#update_sql(values = {}) ⇒ Object
Formats an UPDATE statement using the given values.
-
#where(*cond, &block) ⇒ Object
Add a condition to the WHERE clause.
-
#window_function_sql(function, window) ⇒ Object
The SQL fragment for the given window function’s function and window.
-
#window_sql(opts) ⇒ Object
The SQL fragment for the given window’s options.
-
#with(name, dataset, opts = {}) ⇒ Object
Add a simple common table expression (CTE) with the given name and a dataset that defines the CTE.
-
#with_recursive(name, nonrecursive, recursive, opts = {}) ⇒ Object
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.
-
#with_sql(sql, *args) ⇒ Object
Returns a copy of the dataset with the static SQL used.
Methods included from Metaprogramming
Constructor Details
#initialize(db, opts = nil) ⇒ Dataset
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 adaptor should provide a subclass of Sequel::Dataset, and have the Database#dataset method return an instance of that class.
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# File 'lib/sequel/dataset.rb', line 84 def initialize(db, opts = nil) @db = db @quote_identifiers = db.quote_identifiers? if db.respond_to?(:quote_identifiers?) @identifier_input_method = db.identifier_input_method if db.respond_to?(:identifier_input_method) @identifier_output_method = db.identifier_output_method if db.respond_to?(:identifier_output_method) @opts = opts || {} @row_proc = nil end |
Instance Attribute Details
#db ⇒ Object
The database that corresponds to this dataset
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# File 'lib/sequel/dataset.rb', line 57 def db @db end |
#identifier_input_method ⇒ Object
Set the method to call on identifiers going into the database for this dataset
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# File 'lib/sequel/dataset.rb', line 60 def identifier_input_method @identifier_input_method end |
#identifier_output_method ⇒ Object
Set the method to call on identifiers coming the database for this dataset
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# File 'lib/sequel/dataset.rb', line 63 def identifier_output_method @identifier_output_method end |
#opts ⇒ Object
The hash of options for this dataset, keys are symbols.
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# File 'lib/sequel/dataset.rb', line 66 def opts @opts end |
#quote_identifiers=(value) ⇒ Object (writeonly)
Whether to quote identifiers for this dataset
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# File 'lib/sequel/dataset.rb', line 69 def quote_identifiers=(value) @quote_identifiers = value end |
#row_proc ⇒ Object
The row_proc for this database, should be a Proc that takes a single hash argument and returns the object you want each to return.
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# File 'lib/sequel/dataset.rb', line 74 def row_proc @row_proc end |
Class Method Details
.def_mutation_method(*meths) ⇒ Object
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.
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# File 'lib/sequel/dataset.rb', line 98 def self.def_mutation_method(*meths) meths.each do |meth| class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end") end end |
Instance Method Details
#<<(*args) ⇒ Object
Alias for insert, but not aliased directly so subclasses don’t have to override both methods.
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# File 'lib/sequel/dataset.rb', line 108 def <<(*args) insert(*args) end |
#[](*conditions) ⇒ Object
Returns the first record matching the conditions. Examples:
ds[:id=>1] => {:id=1}
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# File 'lib/sequel/dataset/convenience.rb', line 13 def [](*conditions) raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0 first(*conditions) end |
#[]=(conditions, values) ⇒ Object
Update all records matching the conditions with the values specified. Examples:
ds[:id=>1] = {:id=>2} # SQL: UPDATE ... SET id = 2 WHERE id = 1
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# File 'lib/sequel/dataset/convenience.rb', line 22 def []=(conditions, values) filter(conditions).update(values) end |
#add_graph_aliases(graph_aliases) ⇒ Object
Adds the given graph aliases to the list of graph aliases to use, unlike #set_graph_aliases, which replaces the list. See #set_graph_aliases.
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# File 'lib/sequel/dataset/graph.rb', line 6 def add_graph_aliases(graph_aliases) ds = select_more(*graph_alias_columns(graph_aliases)) ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || ds.opts[:graph][:column_aliases] || {}).merge(graph_aliases) ds end |
#aliased_expression_sql(ae) ⇒ Object
SQL fragment for the aliased expression
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# File 'lib/sequel/dataset/sql.rb', line 35 def aliased_expression_sql(ae) as_sql(literal(ae.expression), ae.aliaz) end |
#all(&block) ⇒ Object
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.
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# File 'lib/sequel/dataset.rb', line 121 def all(&block) a = [] each{|r| a << r} post_load(a) a.each(&block) if block a end |
#and(*cond, &block) ⇒ Object
Adds an further filter to an existing filter using AND. If no filter exists an error is raised. This method is identical to #filter except it expects an existing filter.
ds.filter(:a).and(:b) # SQL: WHERE a AND b
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# File 'lib/sequel/dataset/sql.rb', line 29 def and(*cond, &block) raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where] filter(*cond, &block) end |
#array_sql(a) ⇒ Object
SQL fragment for the SQL array.
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# File 'lib/sequel/dataset/sql.rb', line 40 def array_sql(a) a.empty? ? '(NULL)' : "(#{expression_list(a)})" end |
#as(aliaz) ⇒ Object
Return the dataset as an aliased expression with the given alias. You can use this as a FROM or JOIN dataset, or as a column if this dataset returns a single row and column.
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# File 'lib/sequel/dataset.rb', line 115 def as(aliaz) ::Sequel::SQL::AliasedExpression.new(self, aliaz) end |
#avg(column) ⇒ Object
Returns the average value for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 27 def avg(column) get{|o| o.avg(column)} end |
#call(type, bind_variables = {}, values = nil) ⇒ Object
For the given type (:select, :insert, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash of passed to insert or update (if one of those types is used), which may contain placeholders.
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# File 'lib/sequel/dataset/prepared_statements.rb', line 176 def call(type, bind_variables={}, values=nil) prepare(type, nil, values).call(bind_variables) end |
#case_expression_sql(ce) ⇒ Object
SQL fragment for specifying given CaseExpression.
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# File 'lib/sequel/dataset/sql.rb', line 45 def case_expression_sql(ce) sql = '(CASE ' sql << "#{literal(ce.expression)} " if ce.expression ce.conditions.collect{ |c,r| sql << "WHEN #{literal(c)} THEN #{literal(r)} " } sql << "ELSE #{literal(ce.default)} END)" end |
#cast_sql(expr, type) ⇒ Object
SQL fragment for the SQL CAST expression.
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# File 'lib/sequel/dataset/sql.rb', line 55 def cast_sql(expr, type) "CAST(#{literal(expr)} AS #{db.cast_type_literal(type)})" end |
#clone(opts = {}) ⇒ Object
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.
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# File 'lib/sequel/dataset.rb', line 132 def clone(opts = {}) c = super() c.opts = @opts.merge(opts) c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)} c end |
#column_all_sql(ca) ⇒ Object
SQL fragment for specifying all columns in a given table.
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# File 'lib/sequel/dataset/sql.rb', line 60 def column_all_sql(ca) "#{quote_schema_table(ca.table)}.*" end |
#columns ⇒ Object
Returns the columns in the result set in order. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to get a single row. Adapters are expected to fill the columns cache with the column information when a query is performed. If the dataset does not have any rows, this may be an empty array depending on how the adapter is programmed.
If you are looking for all columns for a single table and maybe some information about each column (e.g. type), see Database#schema.
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# File 'lib/sequel/dataset.rb', line 148 def columns return @columns if @columns ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1) ds.each{break} @columns = ds.instance_variable_get(:@columns) @columns || [] end |
#columns! ⇒ Object
Remove the cached list of columns and do a SELECT query to find the columns.
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# File 'lib/sequel/dataset.rb', line 158 def columns! @columns = nil columns end |
#complex_expression_sql(op, args) ⇒ Object
SQL fragment for complex expressions
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# File 'lib/sequel/dataset/sql.rb', line 65 def complex_expression_sql(op, args) case op when *IS_OPERATORS r = args.at(1) if r.nil? || supports_is_true? raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r] "(#{literal(args.at(0))} #{op} #{v})" elsif op == :IS complex_expression_sql(:"=", args) else complex_expression_sql(:OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)]) end when *TWO_ARITY_OPERATORS "(#{literal(args.at(0))} #{op} #{literal(args.at(1))})" when *N_ARITY_OPERATORS "(#{args.collect{|a| literal(a)}.join(" #{op} ")})" when :NOT "NOT #{literal(args.at(0))}" when :NOOP literal(args.at(0)) when :'B~' "~#{literal(args.at(0))}" else raise(InvalidOperation, "invalid operator #{op}") end end |
#count ⇒ Object
Returns the number of records in the dataset.
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# File 'lib/sequel/dataset/sql.rb', line 93 def count (COUNT_FROM_SELF_OPTS) ? from_self.count : clone(STOCK_COUNT_OPTS).single_value.to_i end |
#def_mutation_method(*meths) ⇒ Object
Add a mutation method to this dataset instance.
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# File 'lib/sequel/dataset.rb', line 164 def def_mutation_method(*meths) meths.each do |meth| instance_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end") end end |
#delete ⇒ Object
Deletes the records in the dataset. The returned value is generally the number of records deleted, but that is adapter dependent.
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# File 'lib/sequel/dataset.rb', line 172 def delete execute_dui(delete_sql) end |
#delete_sql ⇒ Object
Formats a DELETE statement using the given options and dataset options.
dataset.filter{|o| o.price >= 100}.delete_sql #=>
"DELETE FROM items WHERE (price >= 100)"
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# File 'lib/sequel/dataset/sql.rb', line 101 def delete_sql opts = @opts return static_sql(opts[:sql]) if opts[:sql] if opts[:group] raise InvalidOperation, "Grouped datasets cannot be deleted from" elsif opts[:from].is_a?(Array) && opts[:from].size > 1 raise InvalidOperation, "Joined datasets cannot be deleted from" end sql = "DELETE FROM #{source_list(opts[:from])}" if where = opts[:where] sql << " WHERE #{literal(where)}" end sql end |
#distinct(*args) ⇒ Object
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.
dataset.distinct # SQL: SELECT DISTINCT * FROM items
dataset.order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
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# File 'lib/sequel/dataset/sql.rb', line 130 def distinct(*args) raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on? clone(:distinct => args) end |
#each(&block) ⇒ Object
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
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# File 'lib/sequel/dataset.rb', line 178 def each(&block) if @opts[:graph] graph_each(&block) else if row_proc = @row_proc fetch_rows(select_sql){|r| yield row_proc.call(r)} else fetch_rows(select_sql, &block) end end self end |
#each_page(page_size, &block) ⇒ Object
Yields a paginated dataset for each page and returns the receiver. Does a count to find the total number of records for this dataset.
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# File 'lib/sequel/extensions/pagination.rb', line 20 def each_page(page_size, &block) raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] record_count = count total_pages = (record_count / page_size.to_f).ceil (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)} self end |
#empty? ⇒ Boolean
Returns true if no records exist in the dataset, false otherwise
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# File 'lib/sequel/dataset/convenience.rb', line 32 def empty? get(1).nil? end |
#except(dataset, opts = {}) ⇒ Object
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:
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# File 'lib/sequel/dataset/sql.rb', line 145 def except(dataset, opts={}) opts = {:all=>opts} unless opts.is_a?(Hash) raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except? raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all? compound_clone(:except, dataset, opts) end |
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#filter.
dataset.exclude(:category => 'software').sql #=>
"SELECT * FROM items WHERE (category != 'software')"
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# File 'lib/sequel/dataset/sql.rb', line 156 def exclude(*cond, &block) clause = (@opts[:having] ? :having : :where) cond = cond.first if cond.size == 1 cond = filter_expr(cond, &block) cond = SQL::BooleanExpression.invert(cond) cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause] clone(clause => cond) end |
#exists ⇒ Object
Returns an EXISTS clause for the dataset as a LiteralString.
DB.select(1).where(DB[:items].exists).sql
#=> "SELECT 1 WHERE EXISTS (SELECT * FROM items)"
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# File 'lib/sequel/dataset/sql.rb', line 169 def exists LiteralString.new("EXISTS (#{select_sql})") end |
#fetch_rows(sql, &block) ⇒ Object
Executes a select query and fetches records, passing each record to the supplied block. The yielded records should be hashes with symbol keys.
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# File 'lib/sequel/dataset.rb', line 193 def fetch_rows(sql, &block) raise NotImplementedError, NOTIMPL_MSG end |
#filter(*cond, &block) ⇒ Object
Returns a copy of the dataset with the given conditions imposed upon it.
If the query already has a HAVING clause, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause.
filter accepts the following argument types:
-
Hash - list of equality/inclusion expressions
-
Array - depends:
-
If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
-
If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
-
-
String - taken literally
-
Symbol - taken as a boolean column argument (e.g. WHERE active)
-
Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel expression filter DSL.
filter also takes a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions.
If both a block and regular argument are provided, they get ANDed together.
Examples:
dataset.filter(:id => 3).sql #=>
"SELECT * FROM items WHERE (id = 3)"
dataset.filter('price < ?', 100).sql #=>
"SELECT * FROM items WHERE price < 100"
dataset.filter([[:id, (1,2,3)], [:id, 0..10]]).sql #=>
"SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))"
dataset.filter('price < 100').sql #=>
"SELECT * FROM items WHERE price < 100"
dataset.filter(:active).sql #=>
"SELECT * FROM items WHERE :active
dataset.filter{|o| o.price < 100}.sql #=>
"SELECT * FROM items WHERE (price < 100)"
Multiple filter calls can be chained for scoping:
software = dataset.filter(:category => 'software')
software.filter{|o| o.price < 100}.sql #=>
"SELECT * FROM items WHERE ((category = 'software') AND (price < 100))"
See doc/dataset_filters.rdoc for more examples and details.
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# File 'lib/sequel/dataset/sql.rb', line 220 def filter(*cond, &block) _filter(@opts[:having] ? :having : :where, *cond, &block) end |
#first(*args, &block) ⇒ Object
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything. Examples:
ds.first => {:id=>7}
ds.first(2) => [{:id=>6}, {:id=>4}]
ds.order(:id).first(2) => [{:id=>1}, {:id=>2}]
ds.first(:id=>2) => {:id=>2}
ds.first("id = 3") => {:id=>3}
ds.first("id = ?", 4) => {:id=>4}
ds.first{|o| o.id > 2} => {:id=>5}
ds.order(:id).first{|o| o.id > 2} => {:id=>3}
ds.first{|o| o.id > 2} => {:id=>5}
ds.first("id > ?", 4){|o| o.id < 6} => {:id=>5}
ds.order(:id).first(2){|o| o.id < 2} => [{:id=>1}]
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# File 'lib/sequel/dataset/convenience.rb', line 55 def first(*args, &block) ds = block ? filter(&block) : self if args.empty? ds.single_record else args = (args.size == 1) ? args.first : args if Integer === args ds.limit(args).all else ds.filter(args).single_record end end end |
#first_source_alias ⇒ Object Also known as: first_source
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.
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# File 'lib/sequel/dataset/sql.rb', line 226 def first_source_alias source = @opts[:from] if source.nil? || source.empty? raise Error, 'No source specified for query' end case s = source.first when SQL::AliasedExpression s.aliaz when Symbol sch, table, aliaz = split_symbol(s) aliaz ? aliaz.to_sym : s else s end end |
#from(*source) ⇒ Object
Returns a copy of the dataset with the source changed.
dataset.from # SQL: SELECT *
dataset.from(:blah) # SQL: SELECT * FROM blah
dataset.from(:blah, :foo) # SQL: SELECT * FROM blah, foo
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# File 'lib/sequel/dataset/sql.rb', line 248 def from(*source) table_alias_num = 0 sources = [] source.each do |s| case s when Hash s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)} when Dataset sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1)) when Symbol sch, table, aliaz = split_symbol(s) if aliaz s = sch ? SQL::QualifiedIdentifier.new(sch.to_sym, table.to_sym) : SQL::Identifier.new(table.to_sym) sources << SQL::AliasedExpression.new(s, aliaz.to_sym) else sources << s end else sources << s end end o = {:from=>sources.empty? ? nil : sources} o[:num_dataset_sources] = table_alias_num if table_alias_num > 0 clone(o) end |
#from_self ⇒ Object
Returns a dataset selecting from the current dataset.
ds = DB[:items].order(:name)
ds.sql #=> "SELECT * FROM items ORDER BY name"
ds.from_self.sql #=> "SELECT * FROM (SELECT * FROM items ORDER BY name)"
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# File 'lib/sequel/dataset/sql.rb', line 279 def from_self fs = {} @opts.keys.each{|k| fs[k] = nil} clone(fs).from(self) end |
#function_sql(f) ⇒ Object
SQL fragment specifying an SQL function call
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# File 'lib/sequel/dataset/sql.rb', line 286 def function_sql(f) args = f.args "#{f.f}#{args.empty? ? '()' : literal(args)}" end |
#get(column = nil, &block) ⇒ Object
Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.
ds.get(:id)
ds.get{|o| o.sum(:id)}
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# File 'lib/sequel/dataset/convenience.rb', line 75 def get(column=nil, &block) if column raise(Error, GET_ERROR_MSG) if block select(column).single_value else select(&block).single_value end end |
#graph(dataset, join_conditions = nil, options = {}, &block) ⇒ Object
Allows you to join multiple datasets/tables and have the result set split into component tables.
This differs from the usual usage of join, which returns the result set as a single hash. For example:
# CREATE TABLE artists (id INTEGER, name TEXT);
# CREATE TABLE albums (id INTEGER, name TEXT, artist_id INTEGER);
DB[:artists].left_outer_join(:albums, :artist_id=>:id).first
=> {:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}
DB[:artists].graph(:albums, :artist_id=>:id).first
=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>{:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}}
Using a join such as left_outer_join, the attribute names that are shared between the tables are combined in the single return hash. You can get around that by using .select with correct aliases for all of the columns, but it is simpler to use graph and have the result set split for you. In addition, graph respects any row_proc of the current dataset and the datasets you use with graph.
If you are graphing a table and all columns for that table are nil, this indicates that no matching rows existed in the table, so graph will return nil instead of a hash with all nil values:
# If the artist doesn't have any albums
DB[:artists].graph(:albums, :artist_id=>:id).first
=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>nil}
Arguments:
-
dataset - Can be a symbol (specifying a table), another dataset, or an object that responds to .dataset and return a symbol or a dataset
-
join_conditions - Any condition(s) allowed by join_table.
-
options - A hash of graph options. The following options are currently used:
-
: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.
-
: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 join that makes it important to use graph instead of join.
-
: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.
-
-
block - A block that is passed to join_table.
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# File 'lib/sequel/dataset/graph.rb', line 56 def graph(dataset, join_conditions = nil, = {}, &block) # Allow the use of a model, dataset, or symbol as the first argument # Find the table name/dataset based on the argument dataset = dataset.dataset if dataset.respond_to?(:dataset) table_alias = [:table_alias] case dataset when Symbol table = dataset dataset = @db[dataset] table_alias ||= table when ::Sequel::Dataset if dataset.simple_select_all? table = dataset.opts[:from].first table_alias ||= table else table = dataset table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1) end else raise Error, "The dataset argument should be a symbol, dataset, or model" end # Raise Sequel::Error with explanation that the table alias has been used raise_alias_error = lambda do raise(Error, "this #{[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \ "#{[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") end # Only allow table aliases that haven't been used raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) # Join the table early in order to avoid cloning the dataset twice ds = join_table([:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>[:implicit_qualifier], &block) opts = ds.opts # Whether to include the table in the result set add_table = [:select] == false ? false : true # Whether to add the columns to the list of column aliases add_columns = !ds.opts.include?(:graph_aliases) # Setup the initial graph data structure if it doesn't exist unless graph = opts[:graph] master = ds.first_source_alias raise_alias_error.call if master == table_alias # Master hash storing all .graph related information graph = opts[:graph] = {} # Associates column aliases back to tables and columns column_aliases = graph[:column_aliases] = {} # Associates table alias (the master is never aliased) table_aliases = graph[:table_aliases] = {master=>self} # Keep track of the alias numbers used ca_num = graph[:column_alias_num] = Hash.new(0) # All columns in the master table are never # aliased, but are not included if set_graph_aliases # has been used. if add_columns select = opts[:select] = [] columns.each do |column| column_aliases[column] = [master, column] select.push(SQL::QualifiedIdentifier.new(master, column)) end end end # Add the table alias to the list of aliases # Even if it isn't been used in the result set, # we add a key for it with a nil value so we can check if it # is used more than once table_aliases = graph[:table_aliases] table_aliases[table_alias] = add_table ? dataset : nil # Add the columns to the selection unless we are ignoring them if add_table && add_columns select = opts[:select] column_aliases = graph[:column_aliases] ca_num = graph[:column_alias_num] # Which columns to add to the result set cols = [:select] || dataset.columns # If the column hasn't been used yet, don't alias it. # If it has been used, try table_column. # If that has been used, try table_column_N # using the next value of N that we know hasn't been # used cols.each do |column| col_alias, identifier = if column_aliases[column] column_alias = :"#{table_alias}_#{column}" if column_aliases[column_alias] column_alias_num = ca_num[column_alias] column_alias = :"#{column_alias}_#{column_alias_num}" ca_num[column_alias] += 1 end [column_alias, SQL::QualifiedIdentifier.new(table_alias, column).as(column_alias)] else [column, SQL::QualifiedIdentifier.new(table_alias, column)] end column_aliases[col_alias] = [table_alias, column] select.push(identifier) end end ds end |
#grep(cols, terms) ⇒ Object
Pattern match any of the columns to any of the terms. The terms can be strings (which use LIKE) or regular expressions (which are only supported in some databases). See Sequel::SQL::StringExpression.like. Note that the total number of pattern matches will be cols.length * terms.length, which could cause performance issues.
dataset.grep(:a, '%test%') # SQL: SELECT * FROM items WHERE a LIKE '%test%'
dataset.grep([:a, :b], %w'%test% foo') # SQL: SELECT * FROM items WHERE a LIKE '%test%' OR a LIKE 'foo' OR b LIKE '%test%' OR b LIKE 'foo'
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# File 'lib/sequel/dataset/sql.rb', line 299 def grep(cols, terms) filter(SQL::BooleanExpression.new(:OR, *Array(cols).collect{|c| SQL::StringExpression.like(c, *terms)})) end |
#group(*columns) ⇒ Object Also known as: group_by
Returns a copy of the dataset with the results grouped by the value of the given columns.
dataset.group(:id) # SELECT * FROM items GROUP BY id
dataset.group(:id, :name) # SELECT * FROM items GROUP BY id, name
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# File 'lib/sequel/dataset/sql.rb', line 308 def group(*columns) clone(:group => columns) end |
#group_and_count(*columns) ⇒ Object
Returns a dataset grouped by the given column with count by group, order by the count of records. Examples:
ds.group_and_count(:name) => [{:name=>'a', :count=>1}, ...]
ds.group_and_count(:first_name, :last_name) => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]
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# File 'lib/sequel/dataset/convenience.rb', line 89 def group_and_count(*columns) group(*columns).select(*(columns + [COUNT_OF_ALL_AS_COUNT])).order(:count) end |
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the HAVING conditions changed. Raises an error if the dataset has not been grouped. See #filter for argument types.
dataset.group(:sum).having(:sum=>10) # SQL: SELECT * FROM items GROUP BY sum HAVING sum = 10
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# File 'lib/sequel/dataset/sql.rb', line 317 def having(*cond, &block) raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group] _filter(:having, *cond, &block) end |
#import(columns, values, opts = {}) ⇒ Object
Inserts multiple records into the associated table. This method can be to efficiently insert a large amounts of records into a table. Inserts are automatically wrapped in a transaction.
This method is called with a columns array and an array of value arrays:
dataset.import([:x, :y], [[1, 2], [3, 4]])
This method also accepts a dataset instead of an array of value arrays:
dataset.import([:x, :y], other_dataset.select(:a___x, :b___y))
The method also accepts a :slice or :commit_every option that specifies the number of records to insert per transaction. This is useful especially when inserting a large number of records, e.g.:
# this will commit every 50 records
dataset.import([:x, :y], [[1, 2], [3, 4], ...], :slice => 50)
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# File 'lib/sequel/dataset/convenience.rb', line 111 def import(columns, values, opts={}) return @db.transaction{execute_dui("#{insert_sql_base}#{quote_schema_table(@opts[:from].first)} (#{identifier_list(columns)}) VALUES #{literal(values)}")} if values.is_a?(Dataset) return if values.empty? raise(Error, IMPORT_ERROR_MSG) if columns.empty? if slice_size = opts[:commit_every] || opts[:slice] offset = 0 loop do @db.transaction(opts){multi_insert_sql(columns, values[offset, slice_size]).each{|st| execute_dui(st)}} offset += slice_size break if offset >= values.length end else statements = multi_insert_sql(columns, values) @db.transaction{statements.each{|st| execute_dui(st)}} end end |
#insert(*values) ⇒ Object
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.
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# File 'lib/sequel/dataset.rb', line 199 def insert(*values) execute_insert(insert_sql(*values)) end |
#insert_multiple(array, &block) ⇒ Object
Inserts multiple values. If a block is given it is invoked for each item in the given array before inserting it. See #multi_insert as a possible faster version that inserts multiple records in one SQL statement.
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# File 'lib/sequel/dataset/sql.rb', line 326 def insert_multiple(array, &block) if block array.each {|i| insert(block[i])} else array.each {|i| insert(i)} end end |
#insert_sql(*values) ⇒ Object
Formats an INSERT statement using the given values. If a hash is given, the resulting statement includes column names. If no values are given, the resulting statement includes a DEFAULT VALUES clause.
dataset.insert_sql #=> 'INSERT INTO items DEFAULT VALUES'
dataset.insert_sql(1,2,3) #=> 'INSERT INTO items VALUES (1, 2, 3)'
dataset.insert_sql(:a => 1, :b => 2) #=>
'INSERT INTO items (a, b) VALUES (1, 2)'
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# File 'lib/sequel/dataset/sql.rb', line 342 def insert_sql(*values) return static_sql(@opts[:sql]) if @opts[:sql] from = source_list(@opts[:from]) case values.size when 0 values = {} when 1 vals = values.at(0) if [Hash, Dataset, Array].any?{|c| vals.is_a?(c)} values = vals elsif vals.respond_to?(:values) values = vals.values end end case values when Array if values.empty? insert_default_values_sql else "#{insert_sql_base}#{from} VALUES #{literal(values)}#{insert_sql_suffix}" end when Hash values = @opts[:defaults].merge(values) if @opts[:defaults] values = values.merge(@opts[:overrides]) if @opts[:overrides] if values.empty? insert_default_values_sql else fl, vl = [], [] values.each do |k, v| fl << literal(String === k ? k.to_sym : k) vl << literal(v) end "#{insert_sql_base}#{from} (#{fl.join(COMMA_SEPARATOR)}) VALUES (#{vl.join(COMMA_SEPARATOR)})#{insert_sql_suffix}" end when Dataset "#{insert_sql_base}#{from} #{literal(values)}#{insert_sql_suffix}" end end |
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
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# File 'lib/sequel/dataset.rb', line 205 def inspect "#<#{self.class}: #{sql.inspect}>" end |
#intersect(dataset, opts = {}) ⇒ Object
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:
-
: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.intersect(DB).sql #=> “SELECT * FROM items INTERSECT SELECT * FROM other_items”
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# File 'lib/sequel/dataset/sql.rb', line 393 def intersect(dataset, opts={}) opts = {:all=>opts} unless opts.is_a?(Hash) raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except? raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all? compound_clone(:intersect, dataset, opts) end |
#interval(column) ⇒ Object
Returns the interval between minimum and maximum values for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 132 def interval(column) get{|o| o.max(column) - o.min(column)} end |
#invert ⇒ Object
Inverts the current filter
dataset.filter(:category => 'software').invert.sql #=>
"SELECT * FROM items WHERE (category != 'software')"
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# File 'lib/sequel/dataset/sql.rb', line 404 def invert having, where = @opts[:having], @opts[:where] raise(Error, "No current filter") unless having || where o = {} o[:having] = SQL::BooleanExpression.invert(having) if having o[:where] = SQL::BooleanExpression.invert(where) if where clone(o) end |
#join_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
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# File 'lib/sequel/dataset/sql.rb', line 414 def join_clause_sql(jc) table = jc.table table_alias = jc.table_alias table_alias = nil if table == table_alias tref = table_ref(table) " #{join_type_sql(jc.join_type)} #{table_alias ? as_sql(tref, table_alias) : tref}" end |
#join_on_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
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# File 'lib/sequel/dataset/sql.rb', line 423 def join_on_clause_sql(jc) "#{join_clause_sql(jc)} ON #{literal(filter_expr(jc.on))}" end |
#join_table(type, table, expr = nil, options = {}, &block) ⇒ Object
Returns a joined dataset. Uses the following arguments:
-
type - The type of join to do (e.g. :inner)
-
table - Depends on type:
-
Dataset - a subselect is performed with an alias of tN for some value of N
-
Model (or anything responding to :table_name) - table.table_name
-
String, Symbol: table
-
-
expr - specifies conditions, depends on type:
-
Hash, Array with all two pairs - Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.
-
Array - If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.
-
nil - If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses a ON clause based on the block, see below.
-
Everything else - pretty much the same as a using the argument in a call to filter, so strings are considered literal, symbols specify boolean columns, and blockless filter expressions can be used. Uses a JOIN with an ON clause.
-
-
options - a hash of options, with any of the following keys:
-
:table_alias - the name of the table’s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
-
:implicit_qualifer - The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.
-
-
block - The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause.
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# File 'lib/sequel/dataset/sql.rb', line 462 def join_table(type, table, expr=nil, ={}, &block) if [Symbol, String].any?{|c| .is_a?(c)} table_alias = last_alias = nil else table_alias = [:table_alias] last_alias = [:implicit_qualifier] end if Dataset === table if table_alias.nil? table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 table_alias = dataset_alias(table_alias_num) end table_name = table_alias else table = table.table_name if table.respond_to?(:table_name) table_name = table_alias || table end join = if expr.nil? and !block_given? SQL::JoinClause.new(type, table, table_alias) elsif Array === expr and !expr.empty? and expr.all?{|x| Symbol === x} raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block_given? SQL::JoinUsingClause.new(expr, type, table, table_alias) else last_alias ||= @opts[:last_joined_table] || first_source_alias if Sequel.condition_specifier?(expr) expr = expr.collect do |k, v| k = qualified_column_name(k, table_name) if k.is_a?(Symbol) v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) [k,v] end end if block_given? expr2 = yield(table_name, last_alias, @opts[:join] || []) expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 end SQL::JoinOnClause.new(expr, type, table, table_alias) end opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name} opts[:num_dataset_sources] = table_alias_num if table_alias_num clone(opts) end |
#join_using_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
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# File 'lib/sequel/dataset/sql.rb', line 428 def join_using_clause_sql(jc) "#{join_clause_sql(jc)} USING (#{column_list(jc.using)})" end |
#last(*args, &block) ⇒ Object
Reverses the order and then runs first. 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.
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# File 'lib/sequel/dataset/convenience.rb', line 140 def last(*args, &block) raise(Error, 'No order specified') unless @opts[:order] reverse.first(*args, &block) end |
#limit(l, o = nil) ⇒ Object
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.
dataset.limit(10) # SQL: SELECT * FROM items LIMIT 10
dataset.limit(10, 20) # SQL: SELECT * FROM items LIMIT 10 OFFSET 20
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# File 'lib/sequel/dataset/sql.rb', line 513 def limit(l, o = nil) return from_self.limit(l, o) if @opts[:sql] if Range === l o = l.first l = l.last - l.first + (l.exclude_end? ? 0 : 1) end l = l.to_i raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 opts = {:limit => l} if o o = o.to_i raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 opts[:offset] = o end clone(opts) end |
#literal(v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
dataset.literal("abc'def\\") #=> "'abc''def\\\\'"
dataset.literal(:items__id) #=> "items.id"
dataset.literal([1, 2, 3]) => "(1, 2, 3)"
dataset.literal(DB[:items]) => "(SELECT * FROM items)"
dataset.literal(:x + 1 > :y) => "((x + 1) > y)"
If an unsupported object is given, an exception is raised.
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# File 'lib/sequel/dataset/sql.rb', line 541 def literal(v) case v when String return v if v.is_a?(LiteralString) v.is_a?(SQL::Blob) ? literal_blob(v) : literal_string(v) when Symbol literal_symbol(v) when Integer literal_integer(v) when Hash literal_hash(v) when SQL::Expression literal_expression(v) when Float literal_float(v) when BigDecimal literal_big_decimal(v) when NilClass NULL when TrueClass literal_true when FalseClass literal_false when Array literal_array(v) when Time literal_time(v) when DateTime literal_datetime(v) when Date literal_date(v) when Dataset literal_dataset(v) else literal_other(v) end end |
#map(column = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable. Raises an error if both an argument and block are given. Examples:
ds.map(:id) => [1, 2, 3, ...]
ds.map{|r| r[:id] * 2} => [2, 4, 6, ...]
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# File 'lib/sequel/dataset/convenience.rb', line 151 def map(column=nil, &block) if column raise(Error, MAP_ERROR_MSG) if block super(){|r| r[column]} else super(&block) end end |
#max(column) ⇒ Object
Returns the maximum value for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 161 def max(column) get{|o| o.max(column)} end |
#min(column) ⇒ Object
Returns the minimum value for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 166 def min(column) get{|o| o.min(column)} end |
#multi_insert(hashes, opts = {}) ⇒ Object
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:
dataset.multi_insert([{:x => 1}, {:x => 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.
You can also use the :slice or :commit_every option that import accepts.
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# File 'lib/sequel/dataset/convenience.rb', line 180 def multi_insert(hashes, opts={}) return if hashes.empty? columns = hashes.first.keys import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts) end |
#multi_insert_sql(columns, values) ⇒ Object
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.
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# File 'lib/sequel/dataset/sql.rb', line 585 def multi_insert_sql(columns, values) s = "#{insert_sql_base}#{source_list(@opts[:from])} (#{identifier_list(columns)}) VALUES " values.map{|r| s + literal(r)} end |
#naked ⇒ Object
Returns a naked dataset clone - i.e. a dataset that returns records as hashes instead of calling the row proc.
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# File 'lib/sequel/dataset.rb', line 211 def naked ds = clone ds.row_proc = nil ds end |
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR. If no filter exists an error is raised.
dataset.filter(:a).or(:b) # SQL: SELECT * FROM items WHERE a OR b
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# File 'lib/sequel/dataset/sql.rb', line 594 def or(*cond, &block) clause = (@opts[:having] ? :having : :where) raise(InvalidOperation, "No existing filter found.") unless @opts[clause] cond = cond.first if cond.size == 1 clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block))) end |
#order(*columns, &block) ⇒ Object Also known as: order_by
Returns a copy of the dataset with the order changed. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, and even SQL functions. If a block is given, it is treated as a virtual row block, similar to filter.
ds.order(:name).sql #=> 'SELECT * FROM items ORDER BY name'
ds.order(:a, :b).sql #=> 'SELECT * FROM items ORDER BY a, b'
ds.order('a + b'.lit).sql #=> 'SELECT * FROM items ORDER BY a + b'
ds.order(:a + :b).sql #=> 'SELECT * FROM items ORDER BY (a + b)'
ds.order(:name.desc).sql #=> 'SELECT * FROM items ORDER BY name DESC'
ds.order(:name.asc).sql #=> 'SELECT * FROM items ORDER BY name ASC'
ds.order{|o| o.sum(:name)}.sql #=> 'SELECT * FROM items ORDER BY sum(name)'
ds.order(nil).sql #=> 'SELECT * FROM items'
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# File 'lib/sequel/dataset/sql.rb', line 614 def order(*columns, &block) columns += Array(virtual_row_block_call(block)) if block clone(:order => (columns.compact.empty?) ? nil : columns) end |
#order_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the existing order.
ds.order(:a).order(:b).sql #=> 'SELECT * FROM items ORDER BY b'
ds.order(:a).order_more(:b).sql #=> 'SELECT * FROM items ORDER BY a, b'
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# File 'lib/sequel/dataset/sql.rb', line 625 def order_more(*columns, &block) order(*Array(@opts[:order]).concat(columns), &block) end |
#ordered_expression_sql(oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
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# File 'lib/sequel/dataset/sql.rb', line 631 def ordered_expression_sql(oe) "#{literal(oe.expression)} #{oe.descending ? 'DESC' : 'ASC'}" end |
#paginate(page_no, page_size, record_count = nil) ⇒ Object
Returns a paginated dataset. The returned dataset is limited to the page size at the correct offset, and extended with the Pagination module. If a record count is not provided, does a count of total number of records for this dataset.
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# File 'lib/sequel/extensions/pagination.rb', line 11 def paginate(page_no, page_size, record_count=nil) raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] paginated = limit(page_size, (page_no - 1) * page_size) paginated.extend(Pagination) paginated.set_pagination_info(page_no, page_size, record_count || count) end |
#placeholder_literal_string_sql(pls) ⇒ Object
SQL fragment for a literal string with placeholders
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# File 'lib/sequel/dataset/sql.rb', line 636 def placeholder_literal_string_sql(pls) args = pls.args.dup s = pls.str.gsub(QUESTION_MARK){literal(args.shift)} s = "(#{s})" if pls.parens s end |
#prepare(type, name = nil, values = nil) ⇒ Object
Prepare an SQL statement for later execution. This returns a clone of the dataset extended with PreparedStatementMethods, on which you can call call with the hash of bind variables to do substitution. The prepared statement is also stored in the associated database. The following usage is identical:
ps = prepare(:select, :select_by_name)
ps.call(:name=>'Blah')
db.call(:select_by_name, :name=>'Blah')
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# File 'lib/sequel/dataset/prepared_statements.rb', line 189 def prepare(type, name=nil, values=nil) ps = to_prepared_statement(type, values) db.prepared_statements[name] = ps if name ps end |
#print(*cols) ⇒ Object
Pretty prints the records in the dataset as plain-text table.
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# File 'lib/sequel/extensions/pretty_table.rb', line 8 def print(*cols) Sequel::PrettyTable.print(naked.all, cols.empty? ? columns : cols) end |
#qualified_identifier_sql(qcr) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
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# File 'lib/sequel/dataset/sql.rb', line 645 def qualified_identifier_sql(qcr) [qcr.table, qcr.column].map{|x| [SQL::QualifiedIdentifier, SQL::Identifier, Symbol].any?{|c| x.is_a?(c)} ? literal(x) : quote_identifier(x)}.join('.') end |
#qualify(table = first_source) ⇒ Object
Qualify to the given table, or first source if not table is given.
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# File 'lib/sequel/dataset/sql.rb', line 650 def qualify(table=first_source) qualify_to(table) end |
#qualify_to(table) ⇒ Object
Return a copy of the dataset with unqualified identifiers in the SELECT, WHERE, GROUP, HAVING, and ORDER clauses qualified by the given table. If no columns are currently selected, select all columns of the given table.
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# File 'lib/sequel/dataset/sql.rb', line 658 def qualify_to(table) o = @opts return clone if o[:sql] h = {} (o.keys & QUALIFY_KEYS).each do |k| h[k] = qualified_expression(o[k], table) end h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty? clone(h) end |
#qualify_to_first_source ⇒ Object
Qualify the dataset to its current first source. This is useful if you have unqualified identifiers in the query that all refer to the first source, and you want to join to another table which has columns with the same name as columns in the current dataset. See qualify_to.
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# File 'lib/sequel/dataset/sql.rb', line 674 def qualify_to_first_source qualify_to(first_source) end |
#query(&block) ⇒ Object
Translates a query block into a dataset. Query blocks can be useful when expressing complex SELECT statements, e.g.:
dataset = DB[:items].query do
select :x, :y, :z
filter{|o| (o.x > 1) & (o.y > 2)}
order :z.desc
end
Which is the same as:
dataset = DB[:items].select(:x, :y, :z).filter{|o| (o.x > 1) & (o.y > 2)}.order(:z.desc)
Note that inside a call to query, you cannot call each, insert, update, or delete (or any method that calls those), or Sequel will raise an error.
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# File 'lib/sequel/extensions/query.rb', line 30 def query(&block) copy = clone({}) copy.extend(QueryBlockCopy) copy.instance_eval(&block) clone(copy.opts) end |
#quote_identifier(name) ⇒ Object
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.
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# File 'lib/sequel/dataset/sql.rb', line 681 def quote_identifier(name) return name if name.is_a?(LiteralString) name = name.value if name.is_a?(SQL::Identifier) name = input_identifier(name) name = quoted_identifier(name) if quote_identifiers? name end |
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
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# File 'lib/sequel/dataset.rb', line 218 def quote_identifiers? @quote_identifiers end |
#quote_schema_table(table) ⇒ Object
Separates the schema from the table and returns a string with them quoted (if quoting identifiers)
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# File 'lib/sequel/dataset/sql.rb', line 691 def quote_schema_table(table) schema, table = schema_and_table(table) "#{"#{quote_identifier(schema)}." if schema}#{quote_identifier(table)}" end |
#quoted_identifier(name) ⇒ Object
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).
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# File 'lib/sequel/dataset/sql.rb', line 699 def quoted_identifier(name) "\"#{name.to_s.gsub('"', '""')}\"" end |
#range(column) ⇒ Object
Returns a Range object made from the minimum and maximum values for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 188 def range(column) if r = select{|o| [o.min(column).as(:v1), o.max(column).as(:v2)]}.first (r[:v1]..r[:v2]) end end |
#requires_sql_standard_datetimes? ⇒ Boolean
Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format.
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# File 'lib/sequel/dataset.rb', line 224 def requires_sql_standard_datetimes? false end |
#reverse_order(*order) ⇒ Object Also known as: reverse
Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.
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# File 'lib/sequel/dataset/sql.rb', line 705 def reverse_order(*order) order(*invert_order(order.empty? ? @opts[:order] : order)) end |
#schema_and_table(table_name) ⇒ Object
Split the schema information from the table
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# File 'lib/sequel/dataset/sql.rb', line 711 def schema_and_table(table_name) sch = db.default_schema if db case table_name when Symbol s, t, a = split_symbol(table_name) [s||sch, t] when SQL::QualifiedIdentifier [table_name.table, table_name.column] when SQL::Identifier [sch, table_name.value] when String [sch, table_name] else raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String' end end |
#select(*columns, &block) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to filter.
dataset.select(:a) # SELECT a FROM items
dataset.select(:a, :b) # SELECT a, b FROM items
dataset.select{|o| o.a, o.sum(:b)} # SELECT a, sum(b) FROM items
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# File 'lib/sequel/dataset/sql.rb', line 735 def select(*columns, &block) columns += Array(virtual_row_block_call(block)) if block m = [] columns.map do |i| i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i end clone(:select => m) end |
#select_all ⇒ Object
Returns a copy of the dataset selecting the wildcard.
dataset.select(:a).select_all # SELECT * FROM items
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# File 'lib/sequel/dataset/sql.rb', line 747 def select_all clone(:select => nil) end |
#select_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns.
dataset.select(:a).select(:b) # SELECT b FROM items
dataset.select(:a).select_more(:b) # SELECT a, b FROM items
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# File 'lib/sequel/dataset/sql.rb', line 756 def select_more(*columns, &block) select(*Array(@opts[:select]).concat(columns), &block) end |
#select_sql ⇒ Object
Formats a SELECT statement
dataset.select_sql # => "SELECT * FROM items"
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# File 'lib/sequel/dataset/sql.rb', line 763 def select_sql return static_sql(@opts[:sql]) if @opts[:sql] sql = 'SELECT' select_clause_order.each{|x| send(:"select_#{x}_sql", sql)} sql end |
#server(servr) ⇒ Object
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 (which is SELECT uses :read_only database and all other queries use the :default database).
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# File 'lib/sequel/dataset.rb', line 231 def server(servr) clone(:server=>servr) end |
#set(*args) ⇒ Object
Alias for set, but not aliased directly so subclasses don’t have to override both methods.
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# File 'lib/sequel/dataset.rb', line 237 def set(*args) update(*args) end |
#set_defaults(hash) ⇒ Object
Set the default values for insert and update statements. The values passed to insert or update are merged into this hash.
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# File 'lib/sequel/dataset.rb', line 243 def set_defaults(hash) clone(:defaults=>(@opts[:defaults]||{}).merge(hash)) end |
#set_graph_aliases(graph_aliases) ⇒ Object
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. Example:
DB[:artists].graph(:albums, :artist_id=>:id).set_graph_aliases(:artist_name=>[:artists, :name], :album_name=>[:albums, :name], :forty_two=>[:albums, :fourtwo, 42]).first
=> {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}
Arguments:
-
graph_aliases - Should be a hash with keys being symbols of column aliases, and values being arrays with two or three elements. The first element of the array should be the table alias symbol, and the second should be the actual column name symbol. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.
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# File 'lib/sequel/dataset/graph.rb', line 175 def set_graph_aliases(graph_aliases) ds = select(*graph_alias_columns(graph_aliases)) ds.opts[:graph_aliases] = graph_aliases ds end |
#set_overrides(hash) ⇒ Object
Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update.
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# File 'lib/sequel/dataset.rb', line 249 def set_overrides(hash) clone(:overrides=>hash.merge(@opts[:overrides]||{})) end |
#single_record ⇒ Object
Returns the first record in the dataset.
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# File 'lib/sequel/dataset/convenience.rb', line 195 def single_record clone(:limit=>1).each{|r| return r} nil end |
#single_value ⇒ Object
Returns the first value of the first record in the dataset. Returns nil if dataset is empty.
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# File 'lib/sequel/dataset/convenience.rb', line 202 def single_value if r = naked.clone(:graph=>false).single_record r.values.first end end |
#sql ⇒ Object
Same as select_sql, not aliased directly to make subclassing simpler.
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# File 'lib/sequel/dataset/sql.rb', line 771 def sql select_sql end |
#subscript_sql(s) ⇒ Object
SQL fragment for specifying subscripts (SQL arrays)
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# File 'lib/sequel/dataset/sql.rb', line 776 def subscript_sql(s) "#{literal(s.f)}[#{expression_list(s.sub)}]" end |
#sum(column) ⇒ Object
Returns the sum for the given column.
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# File 'lib/sequel/dataset/convenience.rb', line 209 def sum(column) get{|o| o.sum(column)} end |
#supports_cte? ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause).
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# File 'lib/sequel/dataset.rb', line 254 def supports_cte? select_clause_order.include?(WITH_SUPPORTED) end |
#supports_distinct_on? ⇒ Boolean
Whether the dataset supports the DISTINCT ON clause, true by default.
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# File 'lib/sequel/dataset.rb', line 259 def supports_distinct_on? true end |
#supports_intersect_except? ⇒ Boolean
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
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# File 'lib/sequel/dataset.rb', line 264 def supports_intersect_except? true end |
#supports_intersect_except_all? ⇒ Boolean
Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.
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# File 'lib/sequel/dataset.rb', line 269 def supports_intersect_except_all? true end |
#supports_is_true? ⇒ Boolean
Whether the dataset supports the IS TRUE syntax.
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# File 'lib/sequel/dataset.rb', line 274 def supports_is_true? true end |
#supports_window_functions? ⇒ Boolean
Whether the dataset supports window functions.
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# File 'lib/sequel/dataset.rb', line 279 def supports_window_functions? false end |
#to_csv(include_column_titles = true) ⇒ Object
Returns a string in CSV format containing the dataset records. By default the CSV representation includes the column titles in the first line. You can turn that off by passing false as the include_column_titles argument.
This does not use a CSV library or handle quoting of values in any way. If any values in any of the rows could include commas or line endings, you shouldn’t use this.
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# File 'lib/sequel/dataset/convenience.rb', line 221 def to_csv(include_column_titles = true) n = naked cols = n.columns csv = '' csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"} csv end |
#to_hash(key_column, value_column = nil) ⇒ Object
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.
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# File 'lib/sequel/dataset/convenience.rb', line 234 def to_hash(key_column, value_column = nil) inject({}) do |m, r| m[r[key_column]] = value_column ? r[value_column] : r m end end |
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
dataset.group(:a).having(:a=>1).where(:b).unfiltered # SELECT * FROM items
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# File 'lib/sequel/dataset/sql.rb', line 783 def unfiltered clone(:where => nil, :having => nil) end |
#ungraphed ⇒ Object
Remove the splitting of results into subhashes. Also removes metadata related to graphing, so you should not call graph any tables to this dataset after calling this method.
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# File 'lib/sequel/dataset/graph.rb', line 184 def ungraphed clone(:graph=>nil) end |
#union(dataset, opts = {}) ⇒ Object
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:
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# File 'lib/sequel/dataset/sql.rb', line 796 def union(dataset, opts={}) opts = {:all=>opts} unless opts.is_a?(Hash) compound_clone(:union, dataset, opts) end |
#unordered ⇒ Object
Returns a copy of the dataset with no order.
dataset.order(:a).unordered # SELECT * FROM items
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# File 'lib/sequel/dataset/sql.rb', line 804 def unordered order(nil) end |
#update(values = {}) ⇒ Object
Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent.
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# File 'lib/sequel/dataset.rb', line 285 def update(values={}) execute_dui(update_sql(values)) end |
#update_sql(values = {}) ⇒ Object
Formats an UPDATE statement using the given values.
dataset.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.
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# File 'lib/sequel/dataset/sql.rb', line 815 def update_sql(values = {}) opts = @opts return static_sql(opts[:sql]) if opts[:sql] if opts[:group] raise InvalidOperation, "A grouped dataset cannot be updated" elsif (opts[:from].size > 1) or opts[:join] raise InvalidOperation, "A joined dataset cannot be updated" end sql = "UPDATE #{source_list(@opts[:from])} SET " set = if values.is_a?(Hash) values = opts[:defaults].merge(values) if opts[:defaults] values = values.merge(opts[:overrides]) if opts[:overrides] # get values from hash values.map do |k, v| "#{[String, Symbol].any?{|c| k.is_a?(c)} ? quote_identifier(k) : literal(k)} = #{literal(v)}" end.join(COMMA_SEPARATOR) else # copy values verbatim values end sql << set if where = opts[:where] sql << " WHERE #{literal(where)}" end sql end |
#where(*cond, &block) ⇒ Object
Add a condition to the WHERE clause. See #filter for argument types.
dataset.group(:a).having(:a).filter(:b) # SELECT * FROM items GROUP BY a HAVING a AND b
dataset.group(:a).having(:a).where(:b) # SELECT * FROM items WHERE b GROUP BY a HAVING a
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# File 'lib/sequel/dataset/sql.rb', line 850 def where(*cond, &block) _filter(:where, *cond, &block) end |
#window_function_sql(function, window) ⇒ Object
The SQL fragment for the given window function’s function and window.
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# File 'lib/sequel/dataset/sql.rb', line 874 def window_function_sql(function, window) "#{literal(function)} OVER #{literal(window)}" end |
#window_sql(opts) ⇒ Object
The SQL fragment for the given window’s options.
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# File 'lib/sequel/dataset/sql.rb', line 855 def window_sql(opts) raise(Error, 'This dataset does not support window functions') unless supports_window_functions? window = literal(opts[:window]) if opts[:window] partition = "PARTITION BY #{expression_list(Array(opts[:partition]))}" if opts[:partition] order = "ORDER BY #{expression_list(Array(opts[:order]))}" if opts[:order] frame = case opts[:frame] when nil nil when :all "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING" when :rows "ROWS UNBOUNDED PRECEDING" else raise Error, "invalid window frame clause, should be :all, :rows, or nil" end "(#{[window, partition, order, frame].compact.join(' ')})" end |
#with(name, dataset, opts = {}) ⇒ Object
Add a simple 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
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# File 'lib/sequel/dataset/sql.rb', line 883 def with(name, dataset, opts={}) raise(Error, 'This datatset does not support common table expressions') unless supports_cte? clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)]) end |
#with_recursive(name, nonrecursive, recursive, opts = {}) ⇒ Object
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.
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# File 'lib/sequel/dataset/sql.rb', line 893 def with_recursive(name, nonrecursive, recursive, opts={}) raise(Error, 'This datatset does not support common table expressions') unless supports_cte? clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]) end |
#with_sql(sql, *args) ⇒ Object
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.
dataset.with_sql('SELECT * FROM foo') # SELECT * FROM foo
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# File 'lib/sequel/dataset/sql.rb', line 902 def with_sql(sql, *args) sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty? clone(:sql=>sql) end |