MySQL Stored Functions

MySQL Stored Functions

Continuing with our series on Stored Procedures and Functions (see part 1, part 2, or part 3), this month we focus on Stored Functions. Most of what we have covered in those earlier tutorials is relevant here, so I suggest you read those first if you haven't already.
What's a Stored Function
If procedural programming is new to you, you may be wondering what the difference is between a Stored Procedure and a Stored Function. Not too much really. A function always returns a result, and can be called inside an SQL statement just like ordinary SQL functions. A function parameter is the equivalent of the IN procedure parameter, as functions use the RETURN keyword to determine what is passed back. Stored functions also have slightly more limitations in what SQL statements they can run than stored procedures.