SQL ISNULL Functions

SQL ISNULL()

Look at the following "Products" table:

Suppose that the "UnitsOnOrder" column is optional, and may contain NULL values.

Look at the following SELECT statement:

SELECT ProductName, UnitPrice * (UnitsInStock + UnitsOnOrder)
FROM Products;

In the example above, if any of the "UnitsOnOrder" values are NULL, the result will be NULL.

Example

The SQL Server ISNULL() function lets you return an alternative value when an expression is NULL:

SELECT ProductName, UnitPrice * (UnitsInStock + ISNULL(UnitsOnOrder, 0))
FROM Products