NULL predicate

The NULL predicate tests for null values.

Read syntax diagramSkip visual syntax diagramexpressionISNOTNULL
1

The result of a NULL predicate cannot be unknown. If the value of the expression is null, the result is true. If the value is not null, the result is false. If NOT is specified, the result is reversed.

A row type value cannot be used as the operand in a NULL predicate, except as the qualifier of a field name. If expression is a row type, an error is returned (SQLSTATE 428H2).

For compatibility with other SQL dialects, you can use ISNULL as a synonym for IS NULL and NOTNULL as a synonym for IS NOT NULL.

Examples

   PHONENO IS NULL

   SALARY IS NOT NULL
1 You can use ISNULL and NOTNULL as synonyms for IS NULL and IS NOT NULL predicates, respectively; however, it is better for compatibility purposes to use IS NULL and IS NOT NULL