Best way for retrieving single record results in LINQ to SQL

Question

If I query a table with a condition on the key field as in:

        var user = from u in dc.Users
                   where u.UserName == usn
                   s         


        

Answer 1

Also it should be noted that First/FirstOrDefault/Single/SingleOrDefault are the point of execution for a LINQ to Sql command. Since the LINQ statement has not been executed before that, it is able to affect the SQL generated (e.g., It can add a TOP 1 to the sql command)