Hi,

>
> I have some tables that contain records that the user should not be
> able to modify or delete. Other records in the same table should be
> freely modified, deleted, whatever. I'm trying to come up with
> an 'on update or delete' trigger that will prevent the change if a
> field value exists.
>
> if (NEW.SomeField = 0) then
> DoNotChangeMe;
>
> Is something like this possible from within a trigger or is there a
> better way to protect these records at the server level?

You can do this via a trigger that raises an exception...

Here's an example:
CREATE EXCEPTION DELETE_NOT_ALLOWED 'System data - not allowed to delete
this.';


SET TERM ^^ ;
CREATE TRIGGER CATEGORIE_SYSTEEM FOR CATEGORIE ACTIVE BEFORE DELETE POSITION
0 AS
BEGIN
if (old.SYSTEEM = 'T')
then exception DELETE_NOT_ALLOWED;
END
^^
SET TERM ; ^^

Of course, you DO need to handle the exception :-)

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com