NULL predicate

The NULL predicate tests for null values.

Read syntax diagramSkip visual syntax diagramexpressionISNOT NULL

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.

Start of changeSyntax alternatives: 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.End of change

Examples

   EMPLOYEE.PHONE IS NULL
 
   SALARY IS NOT NULL