manual.texi Operators are operators, not functions, so they take

@node Logical Operators, Control flow functions, Comparison Operators, Non-typed Operators

@subsubsection Logical Operators

@findex Logical functions

@findex Functions, logical

@findex Logical operators

@findex Operators, logical

All logical functions return @code{1} (TRUE), @code{0} (FALSE) or

All logical operators evaluate to @code{1} (TRUE), @code{0} (FALSE) or

@code{NULL} (unknown, which is in most cases the same as FALSE):

@table @code

@findex ! (logical NOT)

@item NOT

@itemx !

Logical NOT. Returns @code{1} if the argument is @code{0}, otherwise returns

@code{0}.

Exception: @code{NOT NULL} returns @code{NULL}:

Logical NOT. Evaluates to @code{1} if the operand is @code{0}, otherwise

evaluates to @code{0}.

Exception: @code{NOT NULL} evaluates to @code{NULL}:

@example

mysql> SELECT NOT 1;

        -> 0

mysql> SELECT ! 1+1;

        -> 1

@end example

The last example returns @code{1} because the expression evaluates

The last example produces @code{1} because the expression evaluates

the same way as @code{(!1)+1}.

@findex OR, logical

@findex || (logical OR)

@item OR

@itemx ||

Logical OR. Returns @code{1} if either argument is not @code{0} and not

Logical OR. Evaluates to @code{1} if either operand is not @code{0} and not

@code{NULL}:

@example

mysql> SELECT 1 || 0;

@findex && (logical AND)

@item AND

@itemx &&

Logical AND. For non-@{NULL} operands, returns @code{1} if both operands are

non-zero and @code{0} otherwise.

Returns @code{NULL} if either argument is @code{NULL}:

Logical AND. For non-@code{NULL} operands, evaluates to @code{1} if both

operands are non-zero and to @code{0} otherwise.

Produces @code{NULL} if either operand is @code{NULL}:

@example

mysql> SELECT 1 && 1;

        -> 1