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.

A parameter marker must not be specified for or within the expression.

Notes

Syntax alternatives:
For compatibility with other SQL dialects, you can use ISNULL as an alternative syntax for IS NULL and NOTNULL as alternative syntax for IS NOT NULL.
Example 1: The following predicate is true whenever PHONENO has the null value, and is false otherwise. 
  PHONENO IS NULL
Example 2: The following predicate is true whenever the array MYARRAY has the null value, and is false otherwise.
  MYARRAY IS NULL