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

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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
This commit is contained in:
Bruce Momjian
2007-02-16 03:39:46 +00:00
parent c7b08050d9
commit 4ebb0cf9c3
12 changed files with 779 additions and 157 deletions
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76
src/backend/utils/adt/timestamp.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.171 2007/01/05 22:19:42 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.172 2007/02/16 03:39:45 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -3749,6 +3749,31 @@ interval_trunc(PG_FUNCTION_ARGS)
PG_RETURN_INTERVAL_P(result);
}
/* isoweek2j()
*
* Return the Julian day which corresponds to the first day (Monday) of the given ISO 8601 year and week.
* Julian days are used to convert between ISO week dates and Gregorian dates.
*/
int
isoweek2j(int year, int week)
{
int day0,
day4;
if (!year)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("cannot calculate week number without year information")));
/* fourth day of current year */
day4 = date2j(year, 1, 4);
/* day0 == offset to first day of week (Monday) */
day0 = j2day(day4 - 1);
return ((week - 1) * 7) + (day4 - day0);
}
/* isoweek2date()
* Convert ISO week of year number to date.
* The year field must be specified with the ISO year!
@ -3757,24 +3782,24 @@ interval_trunc(PG_FUNCTION_ARGS)
void
isoweek2date(int woy, int *year, int *mon, int *mday)
{
int day0,
day4,
dayn;
j2date(isoweek2j(*year, woy), year, mon, mday);
}
if (!*year)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("cannot calculate week number without year information")));
/* isoweekdate2date()
*
* Convert an ISO 8601 week date (ISO year, ISO week and day of week) into a Gregorian date.
* Populates year, mon, and mday with the correct Gregorian values.
* year must be passed in as the ISO year.
*/
void
isoweekdate2date(int isoweek, int isowday, int *year, int *mon, int *mday)
{
int jday;
/* fourth day of current year */
day4 = date2j(*year, 1, 4);
jday = isoweek2j(*year, isoweek);
jday += isowday - 1;
/* day0 == offset to first day of week (Monday) */
day0 = j2day(day4 - 1);
dayn = ((woy - 1) * 7) + (day4 - day0);
j2date(dayn, year, mon, mday);
j2date(jday, year, mon, mday);
}
/* date2isoweek()
@ -3887,6 +3912,17 @@ date2isoyear(int year, int mon, int mday)
}
/* date2isoyearday()
*
* Returns the ISO 8601 day-of-year, given a Gregorian year, month and day.
* Possible return values are 1 through 371 (364 in non-leap years).
*/
int
date2isoyearday(int year, int mon, int mday)
{
return date2j(year, mon, mday) - isoweek2j(date2isoyear(year, mon, mday), 1) + 1;
}
/* timestamp_part()
* Extract specified field from timestamp.
*/
@ -4029,6 +4065,10 @@ timestamp_part(PG_FUNCTION_ARGS)
#endif
break;
case DTK_ISOYEAR:
result = date2isoyear(tm->tm_year, tm->tm_mon, tm->tm_mday);
break;
case DTK_TZ:
case DTK_TZ_MINUTE:
case DTK_TZ_HOUR:
@ -4256,6 +4296,10 @@ timestamptz_part(PG_FUNCTION_ARGS)
#endif
break;
case DTK_ISOYEAR:
result = date2isoyear(tm->tm_year, tm->tm_mon, tm->tm_mday);
break;
default:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),