Good day guys!
I am doing a small function in my project, I have a Transactions Table in my database...the Table include: StudentID TransactionNumber Description Date
I already know that there is an auto-increment function using mysql db. By the way may primary key column is the StudentID, but I want to make an auto increment Alphanumeric function for my TransactionNumber like, OR #-0001 then when someone makes a transaction it will automatically get the current value in the database, and increment it by one which will become OR #-0002, etc.

How could I do this while auto increment is not a primary key column? anyhelp is really appreciated