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| author | Bruce Momjian <bruce@momjian.us> | 2008-04-07 00:51:27 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2008-04-07 00:51:27 +0000 |
| commit | a84171b078ba07ddf8f93c12ff3b7e00c4ef131c (patch) | |
| tree | b9ab5df04a9e52745ae599ecb2743c1860f8b616 | |
| parent | 347dd6a1cf4ea78e37982ade15496b454c54cf4c (diff) | |
| download | postgresql-a84171b078ba07ddf8f93c12ff3b7e00c4ef131c.tar.gz postgresql-a84171b078ba07ddf8f93c12ff3b7e00c4ef131c.zip | |
Add documentation clarification for IS [NOT] NULL and row-valued
expressions.
| -rw-r--r-- | doc/src/sgml/func.sgml | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 0811a282db2..097e0560ce2 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.427 2008/04/04 18:45:36 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.428 2008/04/07 00:51:27 momjian Exp $ --> <chapter id="functions"> <title>Functions and Operators</title> @@ -344,7 +344,11 @@ <literal>IS NULL</> is true when the row expression itself is null or when all the row's fields are null, while <literal>IS NOT NULL</> is true when the row expression itself is non-null - and all the row's fields are non-null. + and all the row's fields are non-null. Because of this behavior, + <literal>IS NULL</> and <literal>IS NOT NULL</> do not always return + inverse results for row-valued expressions, i.e. a row-valued + expression that contains both NULL and non-null values will return false + for both tests. This definition conforms to the SQL standard, and is a change from the inconsistent behavior exhibited by <productname>PostgreSQL</productname> versions prior to 8.2. |