Thanks Jason for your help.
In this applications case they would need access to sales peoples cases who have been deleted so would need to keep orphaned records.
So for my app, can this be done without the relationships and done inside php using the extensions.
What I was thinking was, having it when a sales person was deleted the records defaulted to an option "re assign" is it easier to do this in the app?
I do want users having problems updating records becuase of referential integrity so is it best in my situation to have this in the app?
Sorry Jason just getting started out, done alot of reading on mysql and just trying to know work out if i need relationships for this or leave it to the extensions code.