Should I check for DB constraints in code or should I catch exceptions thrown by DB

Question

I have an application that saves data into a table called Jobs. The Jobs table has a column called Name which has a UNIQUE constraint. The Name column is not PRIMARY KEY. I wond

Answer 1

If you are going to check the constraints yourself, do it in the data access layer. Nothing above that layer should know anything about your database or its constraints.

In most cases I'd say leave it to the DAL to catch DB-originated exceptions. But in your specific case, I think we're talking about basic input validation. I'd opt for a name availability check call to the database, before submitting the whole form.