MySQL NULL Functions

MySQL IFNULL() and COALESCE() Functions

Take a look at the following “Products” table:

Consider the following SELECT statement, where the “UnitsOnOrder” column is optional and may contain NULL values:

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

In the example above, if any of the “UnitsOnOrder” values are NULL, the corresponding result will also be NULL.

The MySQL IFNULL() function allows you to specify an alternative value if an expression is NULL.

The example below returns 0 when the value is NULL:

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

Alternatively, we can use the COALESCE() function, as shown here:

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