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		Next
Functions and Operators	Up	Comparison Functions and Operators

Links:

https://www.postgresql.org/docs/9.6/static/functions-logical.html

doc_PostgreSQL

2016-10-12 11:33:40

Comments

Popular Articles

Logical Operators 3.4.5 – Logical Operators The logical operators in Lua are and, or, and not. Like the control structures (see §3.3.4), all logical operators conside

Logical operators Logical operators apply standard boolean algebra operations to their operands. Operator Operator name Example Result ! logical NOT !a

Logical operators Returns the result of a boolean operation. Operator name Syntax Overloadable Prototype examples (for class T) Inside class definition Ou

Logical Operators Examples: Logical operators illustrated The reason for the two different variations of "and" and "or" operators is that the

Logic functions Truth value testing all(a[, axis, out, keepdims]) Test whether all array elements along a given axis evaluate to True. any(a[, axis, out, keepdim