Module: Sequel::Dataset::SQL

Included in:
Sequel::Dataset
Defined in:
lib/sequel/dataset/sql.rb

Overview

The Dataset SQL module implements all the dataset methods concerned with generating SQL statements for retrieving and manipulating records.

Constant Summary collapse

ALIASED_REGEXP = 
/^(.*)\s(.*)$/.freeze
QUALIFIED_REGEXP = 
/^(.*)\.(.*)$/.freeze
WILDCARD = 
'*'.freeze
COMMA_SEPARATOR = 
", ".freeze
NULL = 
"NULL".freeze
TIMESTAMP_FORMAT = 
"TIMESTAMP '%Y-%m-%d %H:%M:%S'".freeze
DATE_FORMAT = 
"DATE '%Y-%m-%d'".freeze
TRUE = 
"'t'".freeze
FALSE = 
"'f'".freeze
AND_SEPARATOR = 
" AND ".freeze
QUESTION_MARK = 
'?'.freeze
JOIN_TYPES = 
{
  :left_outer => 'LEFT OUTER JOIN'.freeze,
  :right_outer => 'RIGHT OUTER JOIN'.freeze,
  :full_outer => 'FULL OUTER JOIN'.freeze,
  :inner => 'INNER JOIN'.freeze
}
STOCK_COUNT_OPTS = 
{:select => ["COUNT(*)".lit], :order => nil}.freeze

Instance Method Summary collapse

Instance Method Details

#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.



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# File 'lib/sequel/dataset/sql.rb', line 251

def and(*cond, &block)
  clause = (@opts[:group] ? :having : :where)
  unless @opts[clause]
    raise Error::NoExistingFilter, "No existing filter found."
  end
  filter(*cond, &block)
end

#column_list(columns) ⇒ Object

Converts an array of column names into a comma seperated string of column names. If the array is empty, a wildcard (*) is returned.



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# File 'lib/sequel/dataset/sql.rb', line 34

def column_list(columns)
  if columns.empty?
    WILDCARD
  else
    m = columns.map do |i|
      i.is_a?(Hash) ? i.map {|kv| "#{literal(kv[0])} AS #{kv[1]}"} : literal(i)
    end
    m.join(COMMA_SEPARATOR)
  end
end

#count ⇒ Object

Returns the number of records in the dataset.



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# File 'lib/sequel/dataset/sql.rb', line 577

def count
  opts = @opts[:sql] ? \
    {:sql => "SELECT COUNT(*) FROM (#{@opts[:sql]}) AS c", :order => nil} : \
    STOCK_COUNT_OPTS

  single_value(opts).to_i
end

#delete_sql(opts = nil) ⇒ Object

Formats a DELETE statement using the given options and dataset options.

dataset.filter {price >= 100}.delete_sql #=>
  "DELETE FROM items WHERE (price >= 100)"



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# File 'lib/sequel/dataset/sql.rb', line 524

def delete_sql(opts = nil)
  opts = opts ? @opts.merge(opts) : @opts

  if opts[:group]
    raise Error::InvalidOperation, "Grouped datasets cannot be deleted from"
  elsif opts[:from].is_a?(Array) && opts[:from].size > 1
    raise Error::InvalidOperation, "Joined datasets cannot be deleted from"
  end

  sql = "DELETE FROM #{opts[:from]}"

  if where = opts[:where]
    sql << " WHERE #{where}"
  end

  sql
end

#except(dataset, all = false) ⇒ Object

Adds an EXCEPT clause using a second dataset object. If all is true the clause used is EXCEPT ALL, which may return duplicate rows.



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# File 'lib/sequel/dataset/sql.rb', line 311

def except(dataset, all = false)
  clone_merge(:except => dataset, :except_all => all)
end

#exclude(*cond, &block) ⇒ Object

Performs the inverse of Dataset#filter.

dataset.exclude(:category => 'software').sql #=>
  "SELECT * FROM items WHERE NOT (category = 'software')"



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# File 'lib/sequel/dataset/sql.rb', line 263

def exclude(*cond, &block)
  clause = (@opts[:group] ? :having : :where)
  cond = cond.first if cond.size == 1
  parenthesize = !(cond.is_a?(Hash) || cond.is_a?(Array))
  if @opts[clause]
    l = expression_list(@opts[clause])
    r = expression_list(block || cond, parenthesize)
    cond = "#{l} AND (NOT #{r})"
  else
    cond = "(NOT #{expression_list(block || cond, true)})"
  end
  clone_merge(clause => cond)
end

#exists(opts = nil) ⇒ Object

Returns an EXISTS clause for the dataset.

dataset.exists #=> "EXISTS (SELECT 1 FROM items)"



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# File 'lib/sequel/dataset/sql.rb', line 556

def exists(opts = nil)
  "EXISTS (#{sql({:select => [1]}.merge(opts || {}))})"
end

#expression_list(expr, parenthesize = false) ⇒ Object

Formats a where clause. If parenthesize is true, then the whole generated clause will be enclosed in a set of parentheses.



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# File 'lib/sequel/dataset/sql.rb', line 123

def expression_list(expr, parenthesize = false)
  case expr
  when Hash
    parenthesize = false if expr.size == 1
    fmt = expr.map {|i| compare_expr(i[0], i[1])}.join(AND_SEPARATOR)
  when Array
    fmt = expr.shift.gsub(QUESTION_MARK) {literal(expr.shift)}
  when Proc
    fmt = proc_to_sql(expr)
  else
    # if the expression is compound, it should be parenthesized in order for 
    # things to be predictable (when using #or and #and.)
    parenthesize |= expr =~ /\).+\(/
    fmt = expr
  end
  parenthesize ? "(#{fmt})" : fmt
end

#filter(*cond, &block) ⇒ Object

Returns a copy of the dataset with the given conditions imposed upon it.

If the query has been grouped, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause. Filter accepts a Hash (formated into a list of equality expressions), an Array (formatted ala ActiveRecord conditions), a String (taken literally), or a block that is converted into expressions.

dataset.filter(:id => 3).sql #=>
  "SELECT * FROM items WHERE (id = 3)"
dataset.filter('price < ?', 100).sql #=>
  "SELECT * FROM items WHERE price < 100"
dataset.filter('price < 100').sql #=>
  "SELECT * FROM items WHERE price < 100"
dataset.filter {price < 100}.sql #=>
  "SELECT * FROM items WHERE (price < 100)"

Multiple filter calls can be chained for scoping:

software = dataset.filter(:category => 'software')
software.filter {price < 100}.sql #=>
  "SELECT * FROM items WHERE (category = 'software') AND (price < 100)"



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# File 'lib/sequel/dataset/sql.rb', line 216

def filter(*cond, &block)
  clause = (@opts[:group] ? :having : :where)
  cond = cond.first if cond.size == 1
  if cond === true || cond === false
    raise Error::InvalidFilter, "Invalid filter specified. Did you mean to supply a block?"
  end
  parenthesize = !(cond.is_a?(Hash) || cond.is_a?(Array))
  filter = cond.is_a?(Hash) && cond
  if @opts[clause]
    l = expression_list(@opts[clause])
    r = expression_list(block || cond, parenthesize)
    clone_merge(clause => "#{l} AND #{r}")
  else
    clone_merge(:filter => cond, clause => expression_list(block || cond))
  end
end

#from(*source) ⇒ Object

Returns a copy of the dataset with the source changed.



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# File 'lib/sequel/dataset/sql.rb', line 142

def from(*source)
  clone_merge(:from => source)
end

#full_outer_join(table, expr) ⇒ Object

Returns an OUTER joined dataset.



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# File 'lib/sequel/dataset/sql.rb', line 355

def full_outer_join(table, expr); join_table(:full_outer, table, expr); 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



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# File 'lib/sequel/dataset/sql.rb', line 189

def group(*columns)
  clone_merge(:group => columns)
end

#having(*cond, &block) ⇒ Object

Returns a copy of the dataset with the having conditions changed. Raises if the dataset has not been grouped. See also #filter



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# File 'lib/sequel/dataset/sql.rb', line 289

def having(*cond, &block)
  unless @opts[:group]
    raise Error, "Can only specify a HAVING clause on a grouped dataset"
  else
    filter(*cond, &block)
  end
end

#inner_join(table, expr) ⇒ Object Also known as: join

Returns an INNER joined dataset.



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# File 'lib/sequel/dataset/sql.rb', line 358

def inner_join(table, expr); join_table(:inner, table, expr); 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.



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# File 'lib/sequel/dataset/sql.rb', line 363

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 444

def insert_sql(*values)
  if values.empty?
    "INSERT INTO #{@opts[:from]} DEFAULT VALUES"
  else
    values = values[0] if values.size == 1
    case values
    when Sequel::Model
      insert_sql(values.values)
    when Array
      if values.empty?
        "INSERT INTO #{@opts[:from]} DEFAULT VALUES"
      elsif values.keys
        fl = values.keys.map {|f| literal(f.to_sym)}
        vl = @transform ? transform_save(values.values) : values.values
        vl.map! {|v| literal(v)}
        "INSERT INTO #{@opts[:from]} (#{fl.join(COMMA_SEPARATOR)}) VALUES (#{vl.join(COMMA_SEPARATOR)})"
      else
        "INSERT INTO #{@opts[:from]} VALUES (#{literal(values)})"
      end
    when Hash
      values = transform_save(values) if @transform
      if values.empty?
        "INSERT INTO #{@opts[:from]} DEFAULT VALUES"
      else
        fl, vl = [], []
        values.each {|k, v| fl << literal(k.to_sym); vl << literal(v)}
        "INSERT INTO #{@opts[:from]} (#{fl.join(COMMA_SEPARATOR)}) VALUES (#{vl.join(COMMA_SEPARATOR)})"
      end
    when Dataset
      "INSERT INTO #{@opts[:from]} #{literal(values)}"
    else
      "INSERT INTO #{@opts[:from]} VALUES (#{literal(values)})"
    end
  end
end

#intersect(dataset, all = false) ⇒ Object

Adds an INTERSECT clause using a second dataset object. If all is true the clause used is INTERSECT ALL, which may return duplicate rows.



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# File 'lib/sequel/dataset/sql.rb', line 305

def intersect(dataset, all = false)
  clone_merge(:intersect => dataset, :intersect_all => all)
end

#invert_order(order) ⇒ Object

Inverts the given order by breaking it into a list of column references and inverting them.

dataset.invert_order([:id.desc]]) #=> [:id]
dataset.invert_order(:category, :price.desc]) #=>
  [:category.desc, :price]



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# File 'lib/sequel/dataset/sql.rb', line 176

def invert_order(order)
  new_order = []
  order.map do |f|
    if f.is_a?(Sequel::SQL::ColumnExpr) && (f.op == Sequel::SQL::ColumnMethods::DESC)
      f.l
    else
      f.desc
    end
  end
end

#join_expr(type, table, expr) ⇒ Object

Returns a join clause based on the specified join type and condition.



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# File 'lib/sequel/dataset/sql.rb', line 323

def join_expr(type, table, expr)
  join_type = JOIN_TYPES[type || :inner]
  unless join_type
    raise Error::InvalidJoinType, "Invalid join type: #{type}"
  end

  join_conditions = {}
  expr.each do |k, v|
    k = qualified_column_name(k, table) if k.is_a?(Symbol)
    v = qualified_column_name(v, @opts[:last_joined_table] || @opts[:from].first) if v.is_a?(Symbol)
    join_conditions[k] = v
  end
  " #{join_type} #{table} ON #{expression_list(join_conditions)}"
end

#join_table(type, table, expr) ⇒ Object

Returns a joined dataset with the specified join type and condition.



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# File 'lib/sequel/dataset/sql.rb', line 339

def join_table(type, table, expr)
  unless expr.is_a?(Hash)
    expr = {expr => :id}
  end
  clause = join_expr(type, table, expr)
  join = @opts[:join] ? @opts[:join] + clause : clause
  clone_merge(:join => join, :last_joined_table => table)
end

#left_outer_join(table, expr) ⇒ Object

Returns a LEFT OUTER joined dataset.



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# File 'lib/sequel/dataset/sql.rb', line 349

def left_outer_join(table, expr); join_table(:left_outer, table, expr); 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.



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# File 'lib/sequel/dataset/sql.rb', line 563

def limit(l, o = nil)
  if l.is_a? Range
    lim = (l.exclude_end? ? l.last - l.first : l.last + 1 - l.first)
    clone_merge(:limit => lim, :offset=>l.first)
  elsif o
    clone_merge(:limit => l, :offset => o)
  else
    clone_merge(:limit => l)
  end
end

#literal(v) ⇒ Object

Returns a literal representation of a value to be used as part of an SQL expression. The stock implementation supports literalization of String (with proper escaping to prevent SQL injections), numbers, Symbol (as column references), Array (as a list of literalized values), Time (as an SQL TIMESTAMP), Date (as an SQL DATE), Dataset (as a subquery) and nil (AS NULL).

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)"

If an unsupported object is given, an exception is raised.



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# File 'lib/sequel/dataset/sql.rb', line 85

def literal(v)
  case v
  when LiteralString
    v
  when String
    "'#{v.gsub(/'/, "''")}'"
  when Integer, Float
    v.to_s
  when BigDecimal
    v.to_s("F")
  when NilClass
    NULL
  when TrueClass
    TRUE
  when FalseClass
    FALSE
  when Symbol
    v.to_column_ref(self)
  when Sequel::SQL::Expression
    v.to_s(self)
  when Array
    v.empty? ? NULL : v.map {|i| literal(i)}.join(COMMA_SEPARATOR)
  when Time
    v.strftime(TIMESTAMP_FORMAT)
  when Date
    v.strftime(DATE_FORMAT)
  when Dataset
    "(#{v.sql})"
  else
    raise Error, "can't express #{v.inspect} as a SQL literal"
  end
end

#or(*cond, &block) ⇒ Object

Adds an alternate filter to an existing filter using OR. If no filter exists an error is raised.



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# File 'lib/sequel/dataset/sql.rb', line 235

def or(*cond, &block)
  clause = (@opts[:group] ? :having : :where)
  cond = cond.first if cond.size == 1
  parenthesize = !(cond.is_a?(Hash) || cond.is_a?(Array))
  if @opts[clause]
    l = expression_list(@opts[clause])
    r = expression_list(block || cond, parenthesize)
    clone_merge(clause => "#{l} OR #{r}")
  else
    raise Error::NoExistingFilter, "No existing filter found."
  end
end

#order(*order) ⇒ Object Also known as: order_by

Returns a copy of the dataset with the order changed.



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# File 'lib/sequel/dataset/sql.rb', line 158

def order(*order)
  clone_merge(:order => order)
end

#qualified_column_name(column, table) ⇒ Object

Returns a qualified column name (including a table name) if the column name isn’t already qualified.



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# File 'lib/sequel/dataset/sql.rb', line 16

def qualified_column_name(column, table)
  s = literal(column)
  if s =~ QUALIFIED_REGEXP
    return column
  else
    if (table =~ ALIASED_REGEXP)
      table = $2
    end
    Sequel::SQL::QualifiedColumnRef.new(table, column)
    # "#{table}.#{column}"
  end
end

#quote_column_ref(name) ⇒ Object

Adds quoting to column references. This method is just a stub and can be overriden in adapters in order to provide correct column quoting behavior.



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# File 'lib/sequel/dataset/sql.rb', line 9

def quote_column_ref(name); name.to_s; end

#reverse_order(*order) ⇒ Object

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 166

def reverse_order(*order)
  order(*invert_order(order.empty? ? @opts[:order] : order))
end

#right_outer_join(table, expr) ⇒ Object

Returns a RIGHT OUTER joined dataset.



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# File 'lib/sequel/dataset/sql.rb', line 352

def right_outer_join(table, expr); join_table(:right_outer, table, expr); end

#select(*columns) ⇒ Object

Returns a copy of the dataset with the selected columns changed.



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# File 'lib/sequel/dataset/sql.rb', line 147

def select(*columns)
  clone_merge(:select => columns)
end

#select_sql(opts = nil) ⇒ Object Also known as: sql

Formats a SELECT statement using the given options and the dataset options.



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# File 'lib/sequel/dataset/sql.rb', line 373

def select_sql(opts = nil)
  opts = opts ? @opts.merge(opts) : @opts
  
  if sql = opts[:sql]
    return sql
  end

  columns = opts[:select]
  select_columns = columns ? column_list(columns) : WILDCARD

  if distinct = opts[:distinct]
    distinct_clause = distinct.empty? ? "DISTINCT" : "DISTINCT ON (#{column_list(distinct)})"
    sql = "SELECT #{distinct_clause} #{select_columns}"
  else
    sql = "SELECT #{select_columns}"
  end
  
  if opts[:from]
    sql << " FROM #{source_list(opts[:from])}"
  end
  
  if join = opts[:join]
    sql << join
  end

  if where = opts[:where]
    sql << " WHERE #{where}"
  end

  if group = opts[:group]
    sql << " GROUP BY #{column_list(group)}"
  end

  if order = opts[:order]
    sql << " ORDER BY #{column_list(order)}"
  end

  if having = opts[:having]
    sql << " HAVING #{having}"
  end

  if limit = opts[:limit]
    sql << " LIMIT #{limit}"
    if offset = opts[:offset]
      sql << " OFFSET #{offset}"
    end
  end

  if union = opts[:union]
    sql << (opts[:union_all] ? \
      " UNION ALL #{union.sql}" : " UNION #{union.sql}")
  elsif intersect = opts[:intersect]
    sql << (opts[:intersect_all] ? \
      " INTERSECT ALL #{intersect.sql}" : " INTERSECT #{intersect.sql}")
  elsif except = opts[:except]
    sql << (opts[:except_all] ? \
      " EXCEPT ALL #{except.sql}" : " EXCEPT #{except.sql}")
  end

  sql
end

#source_list(source) ⇒ Object

Converts an array of sources names into into a comma separated list.



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# File 'lib/sequel/dataset/sql.rb', line 46

def source_list(source)
  if source.nil? || source.empty?
    raise Error, 'No source specified for query'
  end
  auto_alias_count = 0
  m = source.map do |i|
    case i
    when Dataset
      auto_alias_count += 1
      i.to_table_reference(auto_alias_count)
    when Hash
      i.map {|k, v| "#{k.is_a?(Dataset) ? k.to_table_reference : k} #{v}"}.
        join(COMMA_SEPARATOR)
    else
      i
    end
  end
  m.join(COMMA_SEPARATOR)
end

#to_table_reference(idx = nil) ⇒ Object

Returns a table reference for use in the FROM clause. If the dataset has only a :from option refering to a single table, only the table name is returned. Otherwise a subquery is returned.



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# File 'lib/sequel/dataset/sql.rb', line 545

def to_table_reference(idx = nil)
  if opts.keys == [:from] && opts[:from].size == 1
    opts[:from].first.to_s
  else
    idx ? "(#{sql}) t#{idx}" : "(#{sql})"
  end
end

#union(dataset, all = false) ⇒ Object

Adds a UNION clause using a second dataset object. If all is true the clause used is UNION ALL, which may return duplicate rows.



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# File 'lib/sequel/dataset/sql.rb', line 299

def union(dataset, all = false)
  clone_merge(:union => dataset, :union_all => all)
end

#uniq(*args) ⇒ Object Also known as: distinct

Returns a copy of the dataset with the distinct option.



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# File 'lib/sequel/dataset/sql.rb', line 152

def uniq(*args)
  clone_merge(:distinct => args)
end

#update_sql(values = {}, opts = nil, &block) ⇒ Object

Formats an UPDATE statement using the given values.

dataset.update_sql(:price => 100, :category => 'software') #=>
  "UPDATE items SET price = 100, category = 'software'"



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# File 'lib/sequel/dataset/sql.rb', line 484

def update_sql(values = {}, opts = nil, &block)
  opts = opts ? @opts.merge(opts) : @opts

  if opts[:group]
    raise Error::InvalidOperation, "A grouped dataset cannot be updated"
  elsif (opts[:from].size > 1) or opts[:join]
    raise Error::InvalidOperation, "A joined dataset cannot be updated"
  end
  
  sql = "UPDATE #{@opts[:from]} SET "
  if block
    sql << proc_to_sql(block, :comma_separated => true)
  else
    # check if array with keys
    values = values.to_hash if values.is_a?(Array) && values.keys
    if values.is_a?(Hash)
      # get values from hash
      values = transform_save(values) if @transform
      set = values.map do |k, v|
        # convert string key into symbol
        k = k.to_sym if String === k
        "#{literal(k)} = #{literal(v)}"
      end.join(COMMA_SEPARATOR)
    else
      # copy values verbatim
      set = values
    end
    sql << set
  end
  if where = opts[:where]
    sql << " WHERE #{where}"
  end

  sql
end

#where(*cond, &block) ⇒ Object

Returns a copy of the dataset with the where conditions changed. Raises if the dataset has been grouped. See also #filter.



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# File 'lib/sequel/dataset/sql.rb', line 279

def where(*cond, &block)
  if @opts[:group]
    raise Error, "Can't specify a WHERE clause once the dataset has been grouped"
  else
    filter(*cond, &block)
  end
end