diff options
Diffstat (limited to 'doc/src/sgml/func.sgml')
| -rw-r--r-- | doc/src/sgml/func.sgml | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index dc646320cb9..00d476edb6f 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ -<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.61 2001/06/15 21:03:07 tgl Exp $ --> +<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.62 2001/06/19 22:39:08 tgl Exp $ --> <chapter id="functions"> <title>Functions and Operators</title> @@ -273,6 +273,21 @@ <productname>Microsoft Access</productname>) to work, but this may be discontinued in a future release. </para> + + <para> + Boolean values can be tested using the constructs +<synopsis> +<replaceable>expression</replaceable> IS TRUE +<replaceable>expression</replaceable> IS NOT TRUE +<replaceable>expression</replaceable> IS FALSE +<replaceable>expression</replaceable> IS NOT FALSE +<replaceable>expression</replaceable> IS UNKNOWN +<replaceable>expression</replaceable> IS NOT UNKNOWN +</synopsis> + These are similar to <literal>IS NULL</literal> in that they will + always return TRUE or FALSE, never NULL, even when the operand is NULL. + A NULL input is treated as the logical value UNKNOWN. + </para> </sect1> |