Documentation → PostgreSQL 9.6

Supported Versions: Current (13) / 12 / 11 / 10 / 9.6

Development Versions: 14 / devel

Unsupported versions: 9.5 / 9.4 / 9.3 / 9.2 / 9.1 / 9.0 / 8.4 / 8.3 / 8.2

PostgreSQL 9.6.23 Documentation
Prev	Up	Chapter 9. Functions and Operators	Next

9.1. Logical Operators

The usual logical operators are available:

AND

OR

NOT

SQL uses a three-valued logic system with true, false, and null, which represents "unknown". Observe the following truth tables:

`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

The operators AND and OR are commutative, that is, you can switch the left and right operand without affecting the result. But see Section 4.2.14 for more information about the order of evaluation of subexpressions.

Prev	Home	Next
Functions and Operators	Up	Comparison Functions and Operators

Submit correction

If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.