Boolean predicate (bool_predicate)
Boolean values (
BOOLEAN) are compared in a boolean predicate.Syntax
<bool_predicate> ::= <column_spec> [ IS [NOT] <TRUE | FALSE>]
column specExplanation
If only one column specification (
column_spec ) is specified, the syntax is identical to <column_spec> IS TRUE .The
column_spec must always denote a column with the data type BOOLEAN.The following rules apply to the result of a boolean predicate:
Column value |
IS TRUE |
IS NOT TRUE |
IS FALSE |
IS NOT FALSE |
false |
false |
true |
true |
false |
undefined |
undefined |
undefined |
undefined |
undefined |
true |
true |
false |
false |
true |