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.



211
212
213
214
215
216
217
218
219
 
# File 'lib/sequel/adapters/shared/db2.rb', line 211

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.



223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
 
# File 'lib/sequel/adapters/shared/db2.rb', line 223

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) 


252
253
254
 
# File 'lib/sequel/adapters/shared/db2.rb', line 252

def supports_group_cube?
  true
end

#supports_group_rollup? ⇒ Boolean

DB2 supports GROUP BY ROLLUP

Returns:

  • (Boolean) 


257
258
259
 
# File 'lib/sequel/adapters/shared/db2.rb', line 257

def supports_group_rollup?
  true
end

#supports_is_true? ⇒ Boolean

DB2 does not support IS TRUE.

Returns:

  • (Boolean) 


262
263
264
 
# File 'lib/sequel/adapters/shared/db2.rb', line 262

def supports_is_true?
  false
end

#supports_multiple_column_in? ⇒ Boolean

DB2 does not support multiple columns in IN.

Returns:

  • (Boolean) 


267
268
269
 
# File 'lib/sequel/adapters/shared/db2.rb', line 267

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) 


272
273
274
 
# File 'lib/sequel/adapters/shared/db2.rb', line 272

def supports_select_all_and_column?
  false
end

#supports_timestamp_usecs? ⇒ Boolean

DB2 does not support fractional seconds in timestamps.

Returns:

  • (Boolean) 


277
278
279
 
# File 'lib/sequel/adapters/shared/db2.rb', line 277

def supports_timestamp_usecs?
  false
end

#supports_where_true? ⇒ Boolean

DB2 does not support WHERE 1.

Returns:

  • (Boolean) 


287
288
289
 
# File 'lib/sequel/adapters/shared/db2.rb', line 287

def supports_where_true?
  false
end

#supports_window_functions? ⇒ Boolean

DB2 supports window functions

Returns:

  • (Boolean) 


282
283
284
 
# File 'lib/sequel/adapters/shared/db2.rb', line 282

def supports_window_functions?
  true
end