IsNull and COALESCE

IsNull:

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

SELECT ISNULL(NULL, 'W3Schools.com');


In SQL Server, the ISNULL( ) function is used to replace NULL value with another value.

Store_Name	Sales
Store A	300
Store B	NULL

SELECT SUM (ISNULL(Sales,100)) FROM Sales_Data;

returns the following result:

SUM (ISNULL(Sales,100))

400

COALESCE:

Return the first non-null value in a list:

SELECT COALESCE(NULL, NULL, NULL, 'W3Schools.com', NULL, 'Example.com');

Output:W3Schools.com