I've heard about triggers and RI and cascading deletes and etc, but don't really know anything about them. I got the feeling they could be really usefull if they do what I think they do.

Here's a couple of things I do by hand. Are these the sort of things that can be automated?

I have a billing file that contains trips and their cost. I also have a history file that has trips and their cost. They have a common key of tinstkey. If the user modifies the cost in the billing file, I go seek that record in the history file and modify it. Same if they delete or add a trip to the billing file. I don't do the reverse.

In most places I use an integer for the pk so the user never changes it. In some places, though, where the users are used to calling a thing by it's code, I just used the code as the key. Usually the code won't change, but since it is possible for the user to change it, I need to make the update in all tables that use this code. I plan to write a program to search all the tables and change it.

Thanks,

-Michelle