-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.52 2001/02/18 17:17:17 petere Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.53 2001/02/19 00:01:18 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
<citetitle>Programmer's Guide</citetitle>. The
<application>psql</application> commands <command>\df</command> and
<command>\do</command> can be used to show the list of all actually
- available function and operators, respectively.
+ available functions and operators, respectively.
</para>
<para>
<entry>FALSE</entry>
<entry>NULL</entry>
</row>
+
+ <row>
+ <entry>NULL</entry>
+ <entry>NULL</entry>
+ <entry>NULL</entry>
+ <entry>NULL</entry>
+ </row>
</tbody>
</tgroup>
</informaltable>
<literal><replaceable>expression</replaceable> = NULL</literal>
because NULL is not <quote>equal to</quote> NULL. (NULL represents
an unknown value, so it is not known whether two unknown values are
- equal.) <productname>Postgres</productname> implicitly converts
- <literal>= NULL</literal> clauses to <literal>IS NULL</literal> to
+ equal.) <productname>Postgres</productname> presently converts
+ <literal>x = NULL</literal> clauses to <literal>x IS NULL</literal> to
allow some broken client applications (such as
<productname>Microsoft Access</productname>) to work, but this may
be discontinued in a future release.
<row>
<entry> <literal>!!</literal> </entry>
- <entry>Factorial (left operator)</entry>
+ <entry>Factorial (prefix operator)</entry>
<entry>!! 5</entry>
<entry>120</entry>
</row>