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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
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-151
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12 files changed

+773
-151
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‎doc/src/sgml/func.sgml

Lines changed: 55 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.358 2007/02/14 18:46:08 petere Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.359 2007/02/16 03:39:44 momjian Exp $ -->
22

33
<chapter id="functions">
44
<title>Functions and Operators</title>
@@ -4539,7 +4539,7 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
45394539
</row>
45404540
<row>
45414541
<entry><literal>I</literal></entry>
4542-
<entry>last digits of ISO year</entry>
4542+
<entry>last digit of ISO year</entry>
45434543
</row>
45444544
<row>
45454545
<entry><literal>BC</literal> or <literal>B.C.</literal> or
@@ -4607,6 +4607,10 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
46074607
<entry><literal>DDD</literal></entry>
46084608
<entry>day of year (001-366)</entry>
46094609
</row>
4610+
<row>
4611+
<entry><literal>IDDD</literal></entry>
4612+
<entry>ISO day of year (001-371; day 1 of the year is Monday of the first ISO week.)</entry>
4613+
</row>
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<row>
46114615
<entry><literal>DD</literal></entry>
46124616
<entry>day of month (01-31)</entry>
@@ -4615,6 +4619,10 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
46154619
<entry><literal>D</literal></entry>
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<entry>day of week (1-7; Sunday is 1)</entry>
46174621
</row>
4622+
<row>
4623+
<entry><literal>ID</literal></entry>
4624+
<entry>ISO day of week (1-7; Monday is 1)</entry>
4625+
</row>
46184626
<row>
46194627
<entry><literal>W</literal></entry>
46204628
<entry>week of month (1-5) (The first week starts on the first day of the month.)</entry>
@@ -4625,7 +4633,7 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
46254633
</row>
46264634
<row>
46274635
<entry><literal>IW</literal></entry>
4628-
<entry>ISO week number of year (The first Thursday of the new year is in week 1.)</entry>
4636+
<entry>ISO week number of year (1 - 53; the first Thursday of the new year is in week 1.)</entry>
46294637
</row>
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<row>
46314639
<entry><literal>CC</literal></entry>
@@ -4791,6 +4799,27 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
47914799
</para>
47924800
</listitem>
47934801

4802+
<listitem>
4803+
<para>
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An ISO week date (as distinct from a Gregorian date) can be specified to <function>to_timestamp</function> and <function>to_date</function> in one of two ways:
4805+
<itemizedlist>
4806+
<listitem>
4807+
<para>
4808+
Year, week and weekday, for example <literal>to_date('2006-42-4', 'IYYY-IW-ID')</literal> returns the date <literal>2006-10-19</literal>. If you omit the weekday it is assumed to be 1 (Monday).
4809+
</para>
4810+
</listitem>
4811+
<listitem>
4812+
<para>
4813+
Year and day of year, for example <literal>to_date('2006-291', 'IYYY-IDDD')</literal> also returns <literal>2006-10-19</literal>.
4814+
</para>
4815+
</listitem>
4816+
</itemizedlist>
4817+
</para>
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<para>
4819+
Attempting to construct a date using a mixture of ISO week and Gregorian date fields is nonsensical, and could yield unexpected results. In the context of an ISO year, the concept of a 'month' or 'day of month' has no meaning. In the context of a Gregorian year, the ISO week has no meaning. Users should take care to keep Gregorian and ISO date specifications separate.
4820+
</para>
4821+
</listitem>
4822+
47944823
<listitem>
47954824
<para>
47964825
Millisecond (<literal>MS</literal>) and microsecond (<literal>US</literal>)
@@ -5776,6 +5805,29 @@ SELECT EXTRACT(HOUR FROM TIMESTAMP '2001-02-16 20:38:40');
57765805
</listitem>
57775806
</varlistentry>
57785807

5808+
<varlistentry>
5809+
<term><literal>isoyear</literal></term>
5810+
<listitem>
5811+
<para>
5812+
The <acronym>ISO</acronym> 8601 year that the date falls in (not applicable to intervals).
5813+
</para>
5814+
5815+
<screen>
5816+
SELECT EXTRACT(ISOYEAR FROM DATE '2006-01-01');
5817+
<lineannotation>Result: </lineannotation><computeroutput>2005</computeroutput>
5818+
SELECT EXTRACT(ISOYEAR FROM DATE '2006-01-02');
5819+
<lineannotation>Result: </lineannotation><computeroutput>2006</computeroutput>
5820+
</screen>
5821+
5822+
<para>
5823+
Each <acronym>ISO</acronym> year begins with the Monday of the week containing the 4th of January, so in early January or late December the <acronym>ISO</acronym> year may be different from the Gregorian year. See the <literal>week</literal> field for more information.
5824+
</para>
5825+
<para>
5826+
This field is not available in PostgreSQL releases prior to 8.3.
5827+
</para>
5828+
</listitem>
5829+
</varlistentry>
5830+
57795831
<varlistentry>
57805832
<term><literal>microseconds</literal></term>
57815833
<listitem>

‎src/backend/utils/adt/date.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.127 2007/01/05 22:19:40 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.128 2007/02/16 03:39:44 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1748,6 +1748,7 @@ time_part(PG_FUNCTION_ARGS)
17481748
case DTK_DECADE:
17491749
case DTK_CENTURY:
17501750
case DTK_MILLENNIUM:
1751+
case DTK_ISOYEAR:
17511752
default:
17521753
ereport(ERROR,
17531754
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),

‎src/backend/utils/adt/datetime.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.175 2007/01/05 22:19:40 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.176 2007/02/16 03:39:45 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -125,6 +125,7 @@ static const datetkn datetktbl[] = {
125125
{"h", UNITS, DTK_HOUR}, /* "hour" */
126126
{LATE, RESERV, DTK_LATE}, /* "infinity" reserved for "late time" */
127127
{INVALID, RESERV, DTK_INVALID}, /* "invalid" reserved for bad time */
128+
{"isoyear", UNITS, DTK_ISOYEAR}, /* year in terms of the ISO week date */
128129
{"j", UNITS, DTK_JULIAN},
129130
{"jan", MONTH, 1},
130131
{"january", MONTH, 1},

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