Boolean Operators
Syntax
[ AND | OR | NOT ]
Parameters
SQL uses a three-valued Boolean logic where the null value represents "unknown."
a | b | a AND b | a OR b |
---|---|---|---|
TRUE |
TRUE |
TRUE |
TRUE |
TRUE |
FALSE |
FALSE |
TRUE |
TRUE |
NULL |
NULL |
TRUE |
FALSE |
FALSE |
FALSE |
FALSE |
FALSE |
NULL |
FALSE |
NULL |
NULL |
NULL |
NULL |
NULL |
a | NOT a |
---|---|
TRUE |
FALSE |
FALSE |
TRUE |
NULL |
NULL |
Notes
- The operators
AND
andOR
are commutative, that is, you can switch the left and right operand without affecting the result. However, the order of evaluation of subexpressions is not defined. When it is essential to force evaluation order, use a CASE construct. - Do not confuse Boolean operators with the Boolean-Predicate or the Boolean data type, which can have only two values: true and false.