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)