MySQL NULL Functions

MySQL IFNULL() and COALESCE() Functions

• IFNULL() function return the specified value IF the expression is NULL, otherwise return the expression.
• COALESCE() function return the first non-null value in a list.

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.

MySQL IFNULL() Function

The MySQL IFNULL() function lets you return an alternative value if an expression is NULL.

The example below returns 0 if the value is NULL:

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

MySQL COALESCE() Function

Or we can use the COALESCE() function, like this:

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