Booleans and Boolean Operators
Unlike SQL, JSON has three Boolean states: TRUE, FALSE, and JSON UNKNOWN. JSON UNKNOWN is generally a result of an error (for example, invalid data type comparison).
Note: You cannot simply test for a true or false condition, which is the natural inclination for Boolean. For example, to compare @.age for all rows against the number 18, you cannot simply test for ‘@.age <= 18’ and ‘@.age > 18’; you must account for rows where ‘(@.age > 18)’ is unknown.
TRUE and FALSE Boolean conditions are tested using ==. Unlike SQL, Booleans cannot be tested “standalone.”
Example: Assume @.skilled is a Boolean value.
? (@.skilled == TRUE) is a valid statement.
? (@.skilled) is an invalid statement.
UNKNOWN Boolean conditions are testing using the IS UNKNOWN operator.
Examples
: ? (@.skilled IS UNKNOWN) is a valid statement.
? (@.skilled == unknown) is an invalid statement.
&&, ||, and ! are the AND, OR, and NOT operators and work against Boolean operands.
If the initial tested operand is enough to return a result, the other operand does not need to be evaluated. (For example, if operand 1 is FALSE and the operator is &&, then operand 2 can be ignored.)
&& truth table:
Note: Operators can be checked in any order, so FALSE && error may still return an error.
|| truth table:
! truth table:
!TRUE is FALSE
!FALSE is TRUE
!UNKNOWN is UNKNOWN
Last modified date: 10/30/2024