Class Sequel::JDBC::AS400::Dataset
In: lib/sequel/adapters/jdbc/as400.rb
Parent: JDBC::Dataset

Dataset class for AS400 datasets accessed via JDBC.

Methods

select_sql   supports_window_functions?  

Constants

WILDCARD = Sequel::LiteralString.new('*').freeze

Public Instance methods

select_sql()

AS400 needs to use a couple of subselects for all limits and offsets.

[Source]

    # File lib/sequel/adapters/jdbc/as400.rb, line 28
28:         def select_sql
29:           return super unless l = @opts[:limit]
30:           o = @opts[:offset] || 0
31:           order = @opts[:order]
32:           dsa1 = dataset_alias(1)
33:           dsa2 = dataset_alias(2)
34:           rn = row_number_column
35:           irn = Sequel::SQL::Identifier.new(rn).qualify(dsa2)
36:           subselect_sql(unlimited.
37:             from_self(:alias=>dsa1).
38:             select_more(Sequel::SQL::QualifiedIdentifier.new(dsa1, WILDCARD),
39:               Sequel::SQL::WindowFunction.new(SQL::Function.new(:ROW_NUMBER), Sequel::SQL::Window.new(:order=>order)).as(rn)).
40:             from_self(:alias=>dsa2).
41:             select(Sequel::SQL::QualifiedIdentifier.new(dsa2, WILDCARD)).
42:             where((irn > o) & (irn <= l + o)))
43:         end
supports_window_functions?()

[Source]

    # File lib/sequel/adapters/jdbc/as400.rb, line 45
45:         def supports_window_functions?
46:           true
47:         end

[Validate]