IS NULL predicate

An IS NULL predicate determines whether an expression has the value NULL. The predicate evaluates to TRUE if the expression is NULL. If the NOT option is used, the predicate evaluates to TRUE if the expression is NOT NULL.

SQL syntax

{ColumnName | Constant | (Expression)} IS [NOT] NULL

Parameters

Parameter	Description
`ColumnName`	The name of a column from which a value is to be taken. Column names are discussed in Chapter 2, "Names and Parameters".
`Constant`	A specific value. See "Constants".
(`Expression`)	Expression to test.

Examples

Vendors with no personal contact names are identified.

SELECT *
FROM Purchasing.Vendors
WHERE ContactName IS NULL;