This small tips discussed about how to get list of duplicate items for the collection that we do in sql.
For example I have to get list of the email id which is get entered in user table more than one time.
SELECT email, COUNT(email) AS NumOccurrences FROM users GROUP BY email HAVING ( COUNT(email) > 1 )
Linq query work same as on the set of collection and which make use of count
DataClassesDataContext db = new DataClassesDataContext(); var duplicates = db.Users .GroupBy(i => i.emailid) .Where(g => g.Count() > 1) .Select(g => g.emailid); foreach (var d in duplicates) Console.WriteLine(d);
So by using above query you can easily achieve task of finding duplicate for your set of collection.