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IS TRUE, IS FALSE, IS UNKNOWN Predicates
The IS Boolean operator behaves according to the following truth table:
IS
TRUE
FALSE
UNKNOWN
True
True
False
False
False
False
True
False
Unknown
False
False
True
That is:
IS TRUE is true for a BOOLEAN TRUE.
IS FALSE is true for a BOOLEAN FALSE.
IS UNKNOWN is true for an unknown (NULL) value.
Every other comparison is false.
When applied to row value expressions, all elements must test the same.
Last modified date: 01/30/2023