Add a field and insert an increment value

Question

I have this table :

id   ref     data
1    111     data1
2    111     data2
3    111     data3
4    111     data4
5    222     data1
6    222     data2
7             


        

Answer 1

I believe if you create a primary key that looks like (ref, order) where order is an auto_increment, you can have have the database create this for you automatically.

http://mysqldump.azundris.com/archives/5-AUTO_INCREMENT-Trivia.html