How to enforce unique constraint with LINQ to SQL

I'd like to enforce a unique constraint on two columns with LINQ to SQL. I have got a constraint configured on a SQL table, but is there a way to use it with LINQ to SQL?

Unique constraint is applied to two columns, both of which are foreign keys.

Thank you

Edit: I could catch exception, that's if a very specific exception gets thrown. Alternative is to check state of the table before running any updates/inserts. All seems 开发者_如何学运维to be like too much work for a very simple task.

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In my opinion, L2S should not be doing the actual enforcement of this. Your database should be doing it via a unique constraint. Then, when you attempt to do an insert or update via L2S, simple catch the exception (if any) being returned when you call SubmitChanges().