diff options
Diffstat (limited to 'doc/src/sgml/datatype.sgml')
| -rw-r--r-- | doc/src/sgml/datatype.sgml | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 9bf26ffcfd7..bcc013ddbdf 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -2114,7 +2114,7 @@ January 8 04:05:06 1999 PST </para> </sect3> - <sect3> + <sect3 id="datatype-datetime-special-values"> <title>Special Values</title> <indexterm> @@ -2202,12 +2202,26 @@ January 8 04:05:06 1999 PST type: <literal>CURRENT_DATE</literal>, <literal>CURRENT_TIME</literal>, <literal>CURRENT_TIMESTAMP</literal>, <literal>LOCALTIME</literal>, - <literal>LOCALTIMESTAMP</literal>. The latter four accept an - optional subsecond precision specification. (See <xref + <literal>LOCALTIMESTAMP</literal>. (See <xref linkend="functions-datetime-current"/>.) Note that these are SQL functions and are <emphasis>not</emphasis> recognized in data input strings. </para> + <caution> + <para> + While the input strings <literal>now</literal>, + <literal>today</literal>, <literal>tomorrow</literal>, + and <literal>yesterday</literal> are fine to use in interactive SQL + commands, they can have surprising behavior when the command is + saved to be executed later, for example in prepared statements, + views, and function definitions. The string can be converted to a + specific time value that continues to be used long after it becomes + stale. Use one of the SQL functions instead in such contexts. + For example, <literal>CURRENT_DATE + 1</literal> is safer than + <literal>'tomorrow'::date</literal>. + </para> + </caution> + </sect3> </sect2> |