Re: Anyone using Triggers to enforce data validation & business rules?

You have to look at the errors that you generate from your trigger as any
error the system might generate.
It was asked about displaying them on the users screen. Ok. Let's think
about this for a minute. How do you currently display messages that the
database kicks up about
- duplicate record
- file full
- invalid date
...
Does your method differ if the screen is 5250, web, excel spreadsheet,
batch file transfer?
IOW, do not attempt to have your trigger display anything. Your trigger
should signal the error. The application should handle it.
You may want to think twice about using a generic message id CPF9898 or
some such thing. Not only can the application not just look at the
message id, but you then start getting into the whole national language
support issue. Of course, I JUST used CPF9898 in an application here...
:-)
This whole adding database integrity is great. However if you're
applications are from the 1970's and each and every WRITE error is assumed
to be a duplicate key that is then retried as an update you are going to
have issues. And it's not just triggers. Adding constraints and other
database features will present the same issues.


Rob Berendt