If you do not want to have duplicate values for particular column in the database, this is normally achieved by using Unique constraints
. In this case if you try to insert a record with the same value, an exception would be thrown. However, throwing/catching exceptions is a heavy operation, so I would not recommend you to choose this approach.
I believe the cleanest way is to execute a short Linq query to check if the value exist before inserting the new object. You can nevertheless define unique constraints on the database level to ensure data integrity, just in case.
I hope that helps.
the Telerik team