Hi. Suppose I have a table like table components( componentType int, description varchar(200), serialNo int; )
I want to give each component a different id. I could make the serialNo of type autoInc, and that could be acomplished automaticaly. However, that's not exactly what I want. I want that serial to be incremental FOR EACH componentType. For each value of componentType, the serial starts at 0. So I could have: 0,'comp 1',0 0,'comp 2',1 0,'comp 3',3 1,'comp 4',0 1,'comp 5',1 2,'comp 6',0 and so on ... What is the best to acomplish this ? I can only see a way out: Use an interceptor with a preInsert method that does a select on the used serials for a certain componentType and adds 1 to the last value found. However it doesn't seem a very elegant solution. And I think it could lead to racing problems if 2 users try to add componentes at the same time. Could this be acomplished through a different database modeling? Database constraints ? Stored procedures ? I'm using mysql, but would be willing to change to another opensource db if really needed. Any ideas ? Regards, Carlos. Anjos. ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ DbForms Mailing List http://www.wap-force.net/dbforms
