# Logical Functions

## Logical Operators

SQL uses a three-valued logic system with true, false, and null which represents “missing”.

The basic logical operators are available: AND, OR, NOT. The operators AND and OR are commutative, that is, you can switch the left and right operand without affecting the result. Observe the following truth tables:

aba AND ba OR b
truetruetruetrue
truefalsefalsetrue
falsetruefalsetrue
falsefalsefalsefalse
truenullnulltrue
nulltruenulltrue
falsenullfalsenull
nullfalsefalsenull
nullnullnullnull
aNOT aa IS NULLa IS NOT NULL
truefalsefalsetrue
falsetruefalsetrue
nullnulltruefalse

## Logical Functions

Beware, the logical operators are turned into proper identifiers by double quoting to avoid clashing with the corresponding operator.

FunctionReturn typeDescriptionExampleResult
"all"(a boolean, b boolean, c boolean)booleanif c is null then true else if a is false then false else if (b is true or c is true) then null else true"all"(true, false, true)null
"and"(a boolean, b boolean)booleana AND b"and"(true, false)false
"any"(a boolean, b boolean, c boolean)booleanif c is null then false else if a is true then true else if (b is true or c is true) then null else false"any"(true, false, true)true
"not"(a boolean)booleanNOT a"not"(true)false
"or"(a boolean, b boolean)booleana OR b"or"(true, false)true
"xor"(a boolean, b boolean)booleana OR b, but NOT, a AND b"xor"(true, true)false