Module: Sequel::MSSQL::DatasetMethods

Included in:
ADO::MSSQL::Dataset, JDBC::JTDS::Dataset, JDBC::SQLServer::Dataset, ODBC::MSSQL::Dataset, TinyTDS::Dataset
Defined in:
lib/sequel/adapters/shared/mssql.rb

Constant Summary collapse

BOOL_TRUE = 
'1'.freeze
BOOL_FALSE = 
'0'.freeze
COMMA_SEPARATOR = 
', '.freeze
DELETE_CLAUSE_METHODS = 
Dataset.clause_methods(:delete, %w'with from output from2 where')
INSERT_CLAUSE_METHODS = 
Dataset.clause_methods(:insert, %w'with into columns output values')
SELECT_CLAUSE_METHODS = 
Dataset.clause_methods(:select, %w'with distinct limit columns into from lock join where group having order compounds')
UPDATE_CLAUSE_METHODS = 
Dataset.clause_methods(:update, %w'with table set output from where')
NOLOCK = 
' WITH (NOLOCK)'.freeze
UPDLOCK = 
' WITH (UPDLOCK)'.freeze
WILDCARD = 
LiteralString.new('*').freeze
CONSTANT_MAP = 
{:CURRENT_DATE=>'CAST(CURRENT_TIMESTAMP AS DATE)'.freeze, :CURRENT_TIME=>'CAST(CURRENT_TIMESTAMP AS TIME)'.freeze}

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#mssql_unicode_strings ⇒ Object

Allow overriding of the mssql_unicode_strings option at the dataset level.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 247

def mssql_unicode_strings
  @mssql_unicode_strings
end

Instance Method Details

#boolean_constant_sql(constant) ⇒ Object

Ugly hack. While MSSQL supports TRUE and FALSE values, you can’t actually specify them directly in SQL. Unfortunately, you also cannot use an integer value when a boolean is required. Also unforunately, you cannot use an expression that yields a boolean type in cases where in an integer type is needed, such as inserting into a bit field (the closest thing MSSQL has to a boolean).

In filters, SQL::BooleanConstants are used more, while in other places the ruby true/false values are used more, so use expressions that return booleans for SQL::BooleanConstants, and 1/0 for other places. The correct fix for this would require separate literalization paths for filters compared to other values, but that’s more work than I want to do right now.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 267

def boolean_constant_sql(constant)
  case constant
  when true
    '(1 = 1)'
  when false
    '(1 = 0)'
  else
    super
  end
end

#complex_expression_sql(op, args) ⇒ Object

MSSQL uses + for string concatenation, and LIKE is case insensitive by default.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 279

def complex_expression_sql(op, args)
  case op
  when :'||'
    super(:+, args)
  when :ILIKE
    super(:LIKE, args)
  when :"NOT ILIKE"
    super(:"NOT LIKE", args)
  when :<<
    "(#{literal(args[0])} * POWER(2, #{literal(args[1])}))"
  when :>>
    "(#{literal(args[0])} / POWER(2, #{literal(args[1])}))"
  else
    super(op, args)
  end
end

#constant_sql(constant) ⇒ Object

MSSQL doesn’t support the SQL standard CURRENT_DATE or CURRENT_TIME



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# File 'lib/sequel/adapters/shared/mssql.rb', line 297

def constant_sql(constant)
  CONSTANT_MAP[constant] || super
end

#disable_insert_output ⇒ Object

Disable the use of INSERT OUTPUT



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# File 'lib/sequel/adapters/shared/mssql.rb', line 302

def disable_insert_output
  clone(:disable_insert_output=>true)
end

#disable_insert_output! ⇒ Object

Disable the use of INSERT OUTPUT, modifying the receiver



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# File 'lib/sequel/adapters/shared/mssql.rb', line 307

def disable_insert_output!
  mutation_method(:disable_insert_output)
end

#fetch_rows(sql, &block) ⇒ Object

When returning all rows, if an offset is used, delete the row_number column before yielding the row.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 313

def fetch_rows(sql, &block)
  @opts[:offset] ? super(sql){|r| r.delete(row_number_column); yield r} : super(sql, &block)
end

#full_text_search(cols, terms, opts = {}) ⇒ Object

MSSQL uses the CONTAINS keyword for full text search



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# File 'lib/sequel/adapters/shared/mssql.rb', line 318

def full_text_search(cols, terms, opts = {})
  filter("CONTAINS (#{literal(cols)}, #{literal(terms)})")
end

#initialize(db, opts = {}) ⇒ Object

Copy the mssql_unicode_strings option from the db object.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 250

def initialize(db, opts={})
  super
  @mssql_unicode_strings = db.mssql_unicode_strings
end

#insert_select(*values) ⇒ Object

Use the OUTPUT clause to get the value of all columns for the newly inserted record.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 323

def insert_select(*values)
  return unless supports_insert_select?
  naked.clone(default_server_opts(:sql=>output(nil, [SQL::ColumnAll.new(:inserted)]).insert_sql(*values))).single_record
end

#into(table) ⇒ Object

Specify a table for a SELECT … INTO query.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 329

def into(table)
  clone(:into => table)
end

#join_table(type, table, expr = nil, table_alias = {}, &block) ⇒ Object

SQL Server does not support CTEs on subqueries, so move any CTEs on joined datasets to the top level. The user is responsible for resolving any name clashes this may cause.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 336

def join_table(type, table, expr=nil, table_alias={}, &block)
  return super unless Dataset === table && table.opts[:with]
  clone(:with => (opts[:with] || []) + table.opts[:with]).join_table(type, table.clone(:with => nil), expr, table_alias, &block)
end

#multi_insert_sql(columns, values) ⇒ Object

MSSQL uses a UNION ALL statement to insert multiple values at once.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 342

def multi_insert_sql(columns, values)
  [insert_sql(columns, LiteralString.new(values.map {|r| "SELECT #{expression_list(r)}" }.join(" UNION ALL ")))]
end

#nolock ⇒ Object

Allows you to do a dirty read of uncommitted data using WITH (NOLOCK).



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# File 'lib/sequel/adapters/shared/mssql.rb', line 347

def nolock
  lock_style(:dirty)
end

#output(into, values) ⇒ Object

Include an OUTPUT clause in the eventual INSERT, UPDATE, or DELETE query.

The first argument is the table to output into, and the second argument is either an Array of column values to select, or a Hash which maps output column names to selected values, in the style of #insert or #update.

Output into a returned result set is not currently supported.

Examples:

dataset.output(:output_table, [:deleted__id, :deleted__name])
dataset.output(:output_table, :id => :inserted__id, :name => :inserted__name)

Raises:



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# File 'lib/sequel/adapters/shared/mssql.rb', line 363

def output(into, values)
  raise(Error, "SQL Server versions 2000 and earlier do not support the OUTPUT clause") unless supports_output_clause?
  output = {}
  case values
    when Hash
      output[:column_list], output[:select_list] = values.keys, values.values
    when Array
      output[:select_list] = values
  end
  output[:into] = into
  clone({:output => output})
end

#output!(into, values) ⇒ Object

An output method that modifies the receiver.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 377

def output!(into, values)
  mutation_method(:output, into, values)
end

#quoted_identifier(name) ⇒ Object

MSSQL uses [] to quote identifiers



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# File 'lib/sequel/adapters/shared/mssql.rb', line 382

def quoted_identifier(name)
  "[#{name}]"
end

#select_sql ⇒ Object

MSSQL Requires the use of the ROW_NUMBER window function to emulate an offset. This implementation requires MSSQL 2005 or greater (offset can’t be emulated well in MSSQL 2000).

The implementation is ugly, cloning the current dataset and modifying the clone to add a ROW_NUMBER window function (and some other things), then using the modified clone in a subselect which is selected from.

If offset is used, an order must be provided, because the use of ROW_NUMBER requires an order.

Raises:



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# File 'lib/sequel/adapters/shared/mssql.rb', line 396

def select_sql
  return super unless o = @opts[:offset]
  raise(Error, 'MSSQL requires an order be provided if using an offset') unless order = @opts[:order]
  dsa1 = dataset_alias(1)
  rn = row_number_column
  subselect_sql(unlimited.
    unordered.
    select_append{ROW_NUMBER(:over, :order=>order){}.as(rn)}.
    from_self(:alias=>dsa1).
    limit(@opts[:limit]).
    where(SQL::Identifier.new(rn) > o))
end

#server_version ⇒ Object

The version of the database server.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 410

def server_version
  db.server_version(@opts[:server])
end

#supports_insert_select? ⇒ Boolean

MSSQL supports insert_select via the OUTPUT clause.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 415

def supports_insert_select?
  supports_output_clause? && !opts[:disable_insert_output]
end

#supports_intersect_except? ⇒ Boolean

MSSQL 2005+ supports INTERSECT and EXCEPT



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# File 'lib/sequel/adapters/shared/mssql.rb', line 420

def supports_intersect_except?
  is_2005_or_later?
end

#supports_is_true? ⇒ Boolean

MSSQL does not support IS TRUE



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# File 'lib/sequel/adapters/shared/mssql.rb', line 425

def supports_is_true?
  false
end

#supports_join_using? ⇒ Boolean

MSSQL doesn’t support JOIN USING



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# File 'lib/sequel/adapters/shared/mssql.rb', line 430

def supports_join_using?
  false
end

#supports_modifying_joins? ⇒ Boolean

MSSQL 2005+ supports modifying joined datasets



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# File 'lib/sequel/adapters/shared/mssql.rb', line 435

def supports_modifying_joins?
  is_2005_or_later?
end

#supports_multiple_column_in? ⇒ Boolean

MSSQL does not support multiple columns for the IN/NOT IN operators



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# File 'lib/sequel/adapters/shared/mssql.rb', line 440

def supports_multiple_column_in?
  false
end

#supports_output_clause? ⇒ Boolean

MSSQL 2005+ supports the output clause.



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# File 'lib/sequel/adapters/shared/mssql.rb', line 445

def supports_output_clause?
  is_2005_or_later?
end

#supports_window_functions? ⇒ Boolean

MSSQL 2005+ supports window functions



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# File 'lib/sequel/adapters/shared/mssql.rb', line 450

def supports_window_functions?
  true
end