How to get next alpha-numeric ID based on existing value from MySQL

Question

First, I apologize if this has been asked before - indeed I\'m sure it has, but I can\'t find it/can\'t work out what to search for to find it.

I need to generate un

Answer 1

1. Ensure you have an unique constraint on the Reference column.
2. Fetch the current max sequential reference the same way you do it in your sample code. You don't actually need to trim the zeroes before you cast to (int), '0001' is a valid integer.
3. Roll a loop and do your insert inside.
4. Check affected rows after the insert. You can also check the SQL state for a duplicate key error, but having zero affected rows is a good indication that your insert failed due to inserting an existing Reference value.
5. If you have zero affected rows, increment the sequential number, and roll the loop again. If you have non-zero affected rows, you're done and have an unique identifier inserted.