SQL Server ISNULL() Function

Return the specified value IF the expression is NULL, otherwise return the expression:

SELECT ISNULL(NULL, 'W3Schools.com');

Definition and Usage

The ISNULL() function returns a specified value if the expression is NULL.

If the expression is NOT NULL, this function returns the expression.

ISNULL(expression, value)

Parameter	Description
expression	Required. The expression to test whether is NULL
value	Required. The value to return if expression is NULL

Works in:	SQL Server (starting with 2008), Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse

Return the specified value IF the expression is NULL, otherwise return the expression:

SELECT ISNULL('Hello', 'W3Schools.com');

Return the specified value IF the expression is NULL, otherwise return the expression:

SELECT ISNULL(NULL, 500);