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<chapter id="sql-syntax">

you will sometimes need to add parentheses when using combinations

of binary and unary operators. For instance

<programlisting>

SELECT 5 !~ 6;

SELECT 5 !+ 6;

</programlisting>

will be parsed as

<programlisting>

SELECT 5 ! (~ 6);

SELECT 5 ! (+ 6);

</programlisting>

because the parser has no idea --- until it'stoo late--- that

<token>!</token> is defined as a postfix operator not an infix one.

because the parser has no idea -- until it istoo late -- that

<token>!</token> is defined as a postfix operator, not an infix one.

To get the desired behavior in this case, you must write

<programlisting>

SELECT (5 !)~ 6;

SELECT (5 !)+ 6;

</programlisting>

This is the price one pays for extensibility.

</para>