IS [NOT] NULL

Data Types and SubtypesData Definition (DDL) Statements

`IS [NOT] NULL`

Syntax

<value> IS [NOT] NULL

Since NULL is not a value, these operators are not comparison operators.The IS [NOT] NULL predicate tests that the expression on the left side has a value (IS NOT NULL) or has no value (IS NULL).

Example

Search for sales entries that have no shipment date set for them:

SELECT * FROM SALES
WHERE SHIP_DATE IS NULL;

Note	Note regarding the `IS` predicates The `IS` predicates take precedence above the others.

Existential Predicates

This group of predicates includes those that use subqueries to submit values for all kinds of assertions in search conditions.Existential predicates are so called because they use various methods to test for the existence or non-existence of some condition, returning TRUE if the existence or non-existence is confirmed or FALSE otherwise.