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| author | Bruce Momjian <bruce@momjian.us> | 2010-05-29 19:06:16 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2010-05-29 19:06:16 +0000 |
| commit | d800b036d2e7c7dddf3114f1f02ca16824c13769 (patch) | |
| tree | fb0856e6501817a4ae78e015131a85d70ce80400 /doc/src | |
| parent | 23e9fe039172ea751223c44a2732a75979ed018b (diff) | |
| download | postgresql-d800b036d2e7c7dddf3114f1f02ca16824c13769.tar.gz postgresql-d800b036d2e7c7dddf3114f1f02ca16824c13769.zip | |
Document that NOT NULL domain constraints are not always honored.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/create_domain.sgml | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/doc/src/sgml/ref/create_domain.sgml b/doc/src/sgml/ref/create_domain.sgml index 637326b58bb..eb3bb3d9823 100644 --- a/doc/src/sgml/ref/create_domain.sgml +++ b/doc/src/sgml/ref/create_domain.sgml @@ -1,5 +1,5 @@ <!-- -$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.34 2010/04/03 07:22:58 petere Exp $ +$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.35 2010/05/29 19:06:16 momjian Exp $ PostgreSQL documentation --> @@ -121,7 +121,12 @@ CREATE DOMAIN <replaceable class="parameter">name</replaceable> [ AS ] <replacea <term><literal>NOT NULL</></term> <listitem> <para> - Values of this domain are not allowed to be null. + Values of this domain are normally prevented from being null. + However, it is still possible for a domain with this constraint + to take a null value if it is assigned a matching domain type + that has become null, e.g. via a LEFT OUTER JOIN, or + <command>INSERT INTO tab (domcol) VALUES ((SELECT domcol FROM + tab WHERE false))</command>. </para> </listitem> </varlistentry> |