IS
Syntax
IS boolean_value
Description
Tests a value against a boolean value, where boolean_value
can be
TRUE, FALSE, or UNKNOWN.
There is an important difference between using IS TRUE or comparing a value with TRUE using =
. When using =
, only 1
equals to TRUE. But when using IS TRUE, all values which are logically true (like a number > 1) return TRUE.
Examples
SELECT 1 IS TRUE, 0 IS FALSE, NULL IS UNKNOWN; +-----------+------------+-----------------+ | 1 IS TRUE | 0 IS FALSE | NULL IS UNKNOWN | +-----------+------------+-----------------+ | 1 | 1 | 1 | +-----------+------------+-----------------+
Difference between =
and IS TRUE
:
SELECT 2 = TRUE, 2 IS TRUE; +----------+-----------+ | 2 = TRUE | 2 IS TRUE | +----------+-----------+ | 0 | 1 | +----------+-----------+
See Also
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