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<chapter id="sql-syntax">
be used. For example, this is an untrustworthy way of trying to
avoid division by zero in a WHERE clause:
<programlisting>
-SELECT ... WHERE x <> 0 AND y/x > 1.5;
+SELECT ... WHERE x <> 0 AND y/x > 1.5;
</programlisting>
but this is safe:
<programlisting>
-SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END;
+SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END;
</programlisting>
A CASE construct used in this fashion will defeat optimization attempts,
so it should only be done when necessary.