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Ooops, fix busted markup.

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This commit is contained in:
Tom Lane 2002-06-15 22:15:03 +00:00
parent 32fecad80a
commit 62d4526114
1 changed files with 3 additions and 3 deletions
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6
doc/src/sgml/syntax.sgml
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@ -1,5 +1,5 @@
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.62 2002/06/15 21:28:55 tgl Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.63 2002/06/15 22:15:03 tgl Exp $
--> -->
<chapter id="sql-syntax"> <chapter id="sql-syntax">
@ -1471,11 +1471,11 @@ SELECT somefunc() OR true;
be used. For example, this is an untrustworthy way of trying to be used. For example, this is an untrustworthy way of trying to
avoid division by zero in a WHERE clause: avoid division by zero in a WHERE clause:
<programlisting> <programlisting>
SELECT ... WHERE x <> 0 AND y/x > 1.5; SELECT ... WHERE x &lt;&gt; 0 AND y/x &gt; 1.5;
</programlisting> </programlisting>
but this is safe: but this is safe:
<programlisting> <programlisting>
SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END; SELECT ... WHERE CASE WHEN x &lt;&gt; 0 THEN y/x &gt; 1.5 ELSE false END;
</programlisting> </programlisting>
A CASE construct used in this fashion will defeat optimization attempts, A CASE construct used in this fashion will defeat optimization attempts,
so it should only be done when necessary. so it should only be done when necessary.