Skip to content

P
Postgres FD Implementation
Commit f176e379 authored by Tom Lane's avatar Tom Lane
Browse files
Options

Document a bunch of formerly-undocumented date/time operators, 

including the SQL-spec OVERLAPS construct.
parent 05dddf40
Hide whitespace changes
Inline Side-by-side
Showing with 118 additions and 21 deletions
doc/src/sgml/func.sgml
View file @ f176e379
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.169 2003/08/31 17:32:18 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.170 2003/09/08 19:38:02 tgl Exp $
PostgreSQL documentation
-->
......@@ -4575,8 +4575,8 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
<tbody>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>timestamp '2001-09-28 01:00' + interval '23 hours'</literal></entry>
<entry><literal>timestamp '2001-09-29 00:00'</literal></entry>
<entry><literal>date '2001-09-28' + integer '7'</literal></entry>
<entry><literal>date '2001-10-05'</literal></entry>
</row>
<row>
......@@ -4585,16 +4585,58 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
<entry><literal>timestamp '2001-09-28 01:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>date '2001-09-28' + time '03:00'</literal></entry>
<entry><literal>timestamp '2001-09-28 03:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>time '03:00' + date '2001-09-28'</literal></entry>
<entry><literal>timestamp '2001-09-28 03:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>interval '1 day' + interval '1 hour'</literal></entry>
<entry><literal>interval '1 day 01:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>timestamp '2001-09-28 01:00' + interval '23 hours'</literal></entry>
<entry><literal>timestamp '2001-09-29 00:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>time '01:00' + interval '3 hours'</literal></entry>
<entry><literal>time '04:00'</literal></entry>
</row>
<row>
<entry> <literal>+</literal> </entry>
<entry><literal>interval '3 hours' + time '01:00'</literal></entry>
<entry><literal>time '04:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>timestamp '2001-09-28 23:00' - interval '23 hours'</literal></entry>
<entry><literal>timestamp '2001-09-28'</literal></entry>
<entry><literal>- interval '23 hours'</literal></entry>
<entry><literal>interval '-23:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>date '2001-10-01' - date '2001-09-28'</literal></entry>
<entry><literal>integer '3'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>date '2001-10-01' - integer '7'</literal></entry>
<entry><literal>date '2001-09-24'</literal></entry>
</row>
<row>
......@@ -4603,28 +4645,58 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
<entry><literal>timestamp '2001-09-27 23:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>time '05:00' - time '03:00'</literal></entry>
<entry><literal>interval '02:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>time '05:00' - interval '2 hours'</literal></entry>
<entry><literal>time '03:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>timestamp '2001-09-28 23:00' - interval '23 hours'</literal></entry>
<entry><literal>timestamp '2001-09-28 00:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>interval '1 day' - interval '1 hour'</literal></entry>
<entry><literal>interval '23:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>interval '2 hours' - time '05:00'</literal></entry>
<entry><literal>time '03:00:00'</literal></entry>
<entry><literal>time '03:00'</literal></entry>
</row>
<row>
<entry> <literal>-</literal> </entry>
<entry><literal>timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00'</literal></entry>
<entry><literal>interval '1 day 15:00'</literal></entry>
</row>
<row>
<entry> <literal>*</literal> </entry>
<entry><literal>double precision '3.5' * interval '1 hour'</literal></entry>
<entry><literal>interval '03:30'</literal></entry>
</row>
<row>
<entry> <literal>*</literal> </entry>
<entry><literal>interval '1 hour' * int '3'</literal></entry>
<entry><literal>interval '03:00'</literal></entry>
<entry><literal>interval '1 hour' * double precision '3.5'</literal></entry>
<entry><literal>interval '03:30'</literal></entry>
</row>
<row>
<entry> <literal>/</literal> </entry>
<entry><literal>interval '1 hour' / int '3'</literal></entry>
<entry><literal>interval '00:20'</literal></entry>
<entry><literal>interval '1 hour' / double precision '1.5'</literal></entry>
<entry><literal>interval '00:40'</literal></entry>
</row>
</tbody>
</tgroup>
......@@ -4714,7 +4786,7 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
linkend="functions-datetime-trunc">
</entry>
<entry><literal>date_trunc('hour', timestamp '2001-02-16 20:38:40')</literal></entry>
<entry><literal>2001-02-16 20:00:00+00</literal></entry>
<entry><literal>2001-02-16 20:00:00</literal></entry>
</row>
<row>
......@@ -4788,14 +4860,36 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
<entry>Current date and time; see <xref
linkend="functions-datetime-current">
</entry>
<entry><literal>timeofday()</literal></entry>
<entry><literal>Wed Feb 21 17:01:13.000126 2001 EST</literal></entry>
<entry></entry>
<entry></entry>
</row>
</tbody>
</tgroup>
</table>
<para>
In addition to these functions, the SQL <literal>OVERLAPS</> keyword is
supported:
<synopsis>
( <replaceable>start1</replaceable>, <replaceable>end1</replaceable> ) OVERLAPS ( <replaceable>start2</replaceable>, <replaceable>end2</replaceable> )
( <replaceable>start1</replaceable>, <replaceable>length1</replaceable> ) OVERLAPS ( <replaceable>start2</replaceable>, <replaceable>length2</replaceable> )
</synopsis>
This expression yields true when two time periods (defined by their
endpoints) overlap, false when they do not overlap. The endpoints
can be specified as pairs of dates, times, or timestamps; or as
a date, time, or timestamp followed by an interval.
</para>
<screen>
SELECT (DATE '2001-02-16', DATE '2001-12-21') OVERLAPS
(DATE '2001-10-30', DATE '2002-10-30');
<lineannotation>Result: </lineannotation><computeroutput>true</computeroutput>
SELECT (DATE '2001-02-16', INTERVAL '100 days') OVERLAPS
(DATE '2001-10-30', DATE '2002-10-30');
<lineannotation>Result: </lineannotation><computeroutput>false</computeroutput>
</screen>
<sect2 id="functions-datetime-extract">
<title><function>EXTRACT</function>, <function>date_part</function></title>
......@@ -4906,8 +5000,8 @@ SELECT EXTRACT(DOY FROM TIMESTAMP '2001-02-16 20:38:40');
</para>
<screen>
SELECT EXTRACT(EPOCH FROM TIMESTAMP '2001-02-16 20:38:40');
<lineannotation>Result: </lineannotation><computeroutput>982352320</computeroutput>
SELECT EXTRACT(EPOCH FROM TIMESTAMP WITH TIME ZONE '2001-02-16 20:38:40-08');
<lineannotation>Result: </lineannotation><computeroutput>982384720</computeroutput>
SELECT EXTRACT(EPOCH FROM INTERVAL '5 days 3 hours');
<lineannotation>Result: </lineannotation><computeroutput>442800</computeroutput>
......@@ -5156,11 +5250,14 @@ SELECT date_part('hour', INTERVAL '4 hours 3 minutes');
date_trunc('<replaceable>field</replaceable>', <replaceable>source</replaceable>)
</synopsis>
<replaceable>source</replaceable> is a value expression of type
<type>timestamp</type>. (Values of type <type>date</type> and
<type>time</type> are cast automatically.)
<type>timestamp</type> or <type>interval</>.
(Values of type <type>date</type> and
<type>time</type> are cast automatically, to <type>timestamp</type> or
<type>interval</> respectively.)
<replaceable>field</replaceable> selects to which precision to
truncate the time stamp value. The return value is of type
<type>timestamp</type> with all fields that are less than the
truncate the input value. The return value is of type
<type>timestamp</type> or <type>interval</>
with all fields that are less significant than the
selected one set to zero (or one, for day and month).
</para>
......@@ -5185,10 +5282,10 @@ date_trunc('<replaceable>field</replaceable>', <replaceable>source</replaceable>
Examples:
<screen>
SELECT date_trunc('hour', TIMESTAMP '2001-02-16 20:38:40');
<lineannotation>Result: </lineannotation><computeroutput>2001-02-16 20:00:00+00</computeroutput>
<lineannotation>Result: </lineannotation><computeroutput>2001-02-16 20:00:00</computeroutput>
SELECT date_trunc('year', TIMESTAMP '2001-02-16 20:38:40');
<lineannotation>Result: </lineannotation><computeroutput>2001-01-01 00:00:00+00</computeroutput>
<lineannotation>Result: </lineannotation><computeroutput>2001-01-01 00:00:00</computeroutput>
</screen>
</para>
</sect2>
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment