Add two new format fields for use with to_char(), to_date() and

to_timestamp():
    - ID for day-of-week
    - IDDD for day-of-year

This makes it possible to convert ISO week dates to and from text
fully represented in either week ('IYYY-IW-ID') or day-of-year
('IYYY-IDDD') format.

I have also added an 'isoyear' field for use with extract / date_part.

Brendan Jurd

src/backend/utils/adt/date.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.127 2007/01/05 22:19:40 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.128 2007/02/16 03:39:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1748,6 +1748,7 @@ time_part(PG_FUNCTION_ARGS)
 			case DTK_DECADE:
 			case DTK_CENTURY:
 			case DTK_MILLENNIUM:
+			case DTK_ISOYEAR:
 			default:
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),