Is there way to give user-friendly error message on constraint violation

Question

Say I have column Gender and constraint CHECK( Gender IN (\'F\', \'M\', \'OTHER\')).
If I accidentally forgot to handle this on client side, us

Answer 1

Constraints are what databases use to protect themselves from errant applications, not from users.

That means that constraint violations should be captured by the application and possibly cleaned up for presentation to the user. I'd consider an application which didn't do that to be deficient in some manner.

I say 'possibly' since your application (at least for this case) should never see that happen. It should almost certainly be using a drop down limited-choice control for something like that. If it used a combo-box or (shock, horror) a free-format text entry field, it would need to be redefined.

That would mean that the violation would never occur unless, of course, the application and the constraint get out of sync at some point. But that's something that should be caught in testing, long before a customer ever gets their grubby little hands on your application.

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To answer your actual question, the messages that come out of Oracle for constraint violations cannot be changed. The best you can do is to name your constraints intelligently so that it may make sense to an end user.

But I still maintain that this presentation of problems to a user is a responsibility of the application layer, not the database layer.