You are using LINQ to SQL to query a database. You need to retrieve an entity by its primary key when querying an entity set. If the query does not return exactly one match, the query must throw an exception.

Which LINQ operator should you use?

The Single operator returns the only element of a sequence; this method throws an exception if more than one element is in the sequence.

Use the First operator to return the first matching element as a Product, instead of as a sequence containing a Product. This operator will not throw an exception if the set includes multiple matches