Null condition

The null condition tests for nulls, when a value is missing or unknown.

Syntax

expression IS [ NOT ] NULL

Arguments

expression

Any expression such as a column.

IS NULL

Is true when the expression's value is null and false when it has a value.

IS NOT NULL

Is false when the expression's value is null and true when it has a value.

Example

This example indicates how many times the SALES table contains null in the QTYSOLD field:

select count(*) from sales
where qtysold is null;
count
-------
0
(1 row)