Boolean Functions and Operators
Boolean type | |
Logical disjunction. | |
Logical conjunction. | |
Logical negation. | |
Comparison operators | |
Generalized boolean and applied to the set of values. | |
Generalized boolean or applied to the set of values. |
type
bool
bool
A boolean type with possible values of true
and false
.
EdgeQL has case-insensitive keywords and that includes the boolean literals:
db>
select (True, true, TRUE);
{(true, true, true)}
db>
select (False, false, FALSE);
{(false, false, false)}
A boolean value may arise as a result of a logical or comparison operations as well as in and not in:
db>
select true and 2 < 3;
{true}
db>
select '!' IN {'hello', 'world'};
{false}
It is also possible to cast between bool, str, and json:
db>
select <json>true;
{'true'}
db>
select <bool>'True';
{true}
Filter clauses must always evaluate to a boolean:
select User
filter .name ilike 'alice';
operator
bool or bool
bool or bool -> bool
Logical disjunction.
db>
select false or true;
{true}
operator
bool and bool
bool and bool -> bool
Logical conjunction.
db>
select false and true;
{false}
operator
not bool
not bool -> bool
Logical negation.
db>
select not false;
{true}
The and
and or
operators are commutative.
The truth tables are as follows:
a | b | a | a |
|
---|---|---|---|---|
true | true | true | true | false |
true | false | false | true | false |
false | true | false | true | true |
false | false | false | false | true |
It is important to understand the difference between using and
/or
vs all()/any(). This difference is in how they handle {}
. Both and
and or
operators apply to the cross-product of their operands. Thus if any of the operands are {}
, the result is also {}
for and
and or
.
The all() and any() are generalized to apply to sets of values, including {}
. Thus they have the following truth table:
a | b |
|
|
---|---|---|---|
true | true | true | true |
true | false | false | true |
{} | true | true | true |
{} | false | false | false |
false | true | false | true |
false | false | false | false |
true | {} | true | true |
false | {} | false | false |
{} | {} | true | false |
Since all() and any() apply to sets as a whole, missing values (represented by {}
) are just that - missing. They don’t affect the overall result.
To understand the last line in the above truth table it’s useful to remember that all({a, b}) = all(a) and all(b)
and any({a, b}) = any(a) or any(b)
.
For more customized handling of {}
the ?? should be used.