pointed out by Chris KL on -hackers a little while ago -- NOT NULL !=
CHECK xxx IS NOT NULL.
Neil Conway
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+$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.6 2002/09/20 03:39:15 momjian Exp $
PostgreSQL documentation
-->
<term><literal>NOT NULL</></term>
<listitem>
<para>
- Values of this domain are not allowed to be NULL. This is
- equivalent to the column constraint <literal>CHECK (<replaceable
- class="PARAMETER">column</replaceable> NOT NULL)</literal>.
+ Values of this domain are not allowed to be NULL.
</para>
</listitem>
</varlistentry>