Module: Sequel::DB2::DatasetMethods

Includes:
EmulateOffsetWithRowNumber
Included in:
Dataset, IBMDB::Dataset
Defined in:
lib/sequel/adapters/shared/db2.rb

Constant Summary collapse

PAREN_CLOSE = 
Dataset::PAREN_CLOSE
PAREN_OPEN = 
Dataset::PAREN_OPEN
BITWISE_METHOD_MAP = 
{:& =>:BITAND, :| => :BITOR, :^ => :BITXOR, :'B~'=>:BITNOT}
EMULATED_FUNCTION_MAP = 
{:char_length=>'length'.freeze}
BOOL_TRUE = 
'1'.freeze
BOOL_FALSE = 
'0'.freeze
CAST_STRING_OPEN = 
"RTRIM(CHAR(".freeze
CAST_STRING_CLOSE = 
"))".freeze
FETCH_FIRST_ROW_ONLY = 
" FETCH FIRST ROW ONLY".freeze
FETCH_FIRST = 
" FETCH FIRST ".freeze
ROWS_ONLY = 
" ROWS ONLY".freeze
EMPTY_FROM_TABLE = 
' FROM "SYSIBM"."SYSDUMMY1"'.freeze

Instance Method Summary collapse

Methods included from EmulateOffsetWithRowNumber

#select_sql

Instance Method Details

#cast_sql_append(sql, expr, type) ⇒ Object

DB2 casts strings using RTRIM and CHAR instead of VARCHAR.



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# File 'lib/sequel/adapters/shared/db2.rb', line 216

def cast_sql_append(sql, expr, type)
  if(type == String)
    sql << CAST_STRING_OPEN
    literal_append(sql, expr)
    sql << CAST_STRING_CLOSE
  else
    super
  end
end

#complex_expression_sql_append(sql, op, args) ⇒ Object

Handle DB2 specific LIKE and bitwise operator support, and emulate the extract method, which DB2 doesn’t natively support.



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# File 'lib/sequel/adapters/shared/db2.rb', line 228

def complex_expression_sql_append(sql, op, args)
  case op
  when :ILIKE
    super(sql, :LIKE, [SQL::Function.new(:upper, args.at(0)), SQL::Function.new(:upper, args.at(1)) ])
  when :"NOT ILIKE"
    super(sql, :"NOT LIKE", [SQL::Function.new(:upper, args.at(0)), SQL::Function.new(:upper, args.at(1)) ])
  when :&, :|, :^
    # works with db2 v9.5 and after
    op = BITWISE_METHOD_MAP[op]
    sql << complex_expression_arg_pairs(args){|a, b| literal(SQL::Function.new(op, a, b))}
  when :<<
    sql << complex_expression_arg_pairs(args){|a, b| "(#{literal(a)} * POWER(2, #{literal(b)}))"}
  when :>>
    sql << complex_expression_arg_pairs(args){|a, b| "(#{literal(a)} / POWER(2, #{literal(b)}))"}
  when :%
    sql << complex_expression_arg_pairs(args){|a, b| "MOD(#{literal(a)}, #{literal(b)})"}
  when :'B~'
    literal_append(sql, SQL::Function.new(:BITNOT, *args))
  when :extract
    sql << args.at(0).to_s
    sql << PAREN_OPEN
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  else
    super
  end
end

#supports_group_cube? ⇒ Boolean

DB2 supports GROUP BY CUBE

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 257

def supports_group_cube?
  true
end

#supports_group_rollup? ⇒ Boolean

DB2 supports GROUP BY ROLLUP

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 262

def supports_group_rollup?
  true
end

#supports_is_true? ⇒ Boolean

DB2 does not support IS TRUE.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 267

def supports_is_true?
  false
end

#supports_multiple_column_in? ⇒ Boolean

DB2 does not support multiple columns in IN.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 272

def supports_multiple_column_in?
  false
end

#supports_select_all_and_column? ⇒ Boolean

DB2 only allows * in SELECT if it is the only thing being selected.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 277

def supports_select_all_and_column?
  false
end

#supports_timestamp_usecs? ⇒ Boolean

DB2 does not support fractional seconds in timestamps.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 282

def supports_timestamp_usecs?
  false
end

#supports_where_true? ⇒ Boolean

DB2 does not support WHERE 1.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 292

def supports_where_true?
  false
end

#supports_window_functions? ⇒ Boolean

DB2 supports window functions

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/db2.rb', line 287

def supports_window_functions?
  true
end