</indexterm>
Ordinary comparison operators yield null (signifying <quote>unknown</>),
not true or false, when either input is null. For example,
- <literal>7 = NULL</> yields null. When this behavior is not suitable,
- use the
+ <literal>7 = NULL</> yields null, as does <literal>7 <> NULL</>. When
+ this behavior is not suitable, use the
<literal>IS <optional> NOT </> DISTINCT FROM</literal> constructs:
<synopsis>
<replaceable>expression</replaceable> IS DISTINCT FROM <replaceable>expression</replaceable>