Find duplicate with Linq

By | March 5, 2011

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)

So by using above query you can easily achieve task of finding duplicate for your set of collection.

Author: Pranay Rana

Pranay is MVB on DZone and working as a Senior Software engineer. Doing Web development using Asp.Net ,C#, MS sql server, JQuery/Javascript that he had experience of 4.3 years now. For himdef. of programming is : Programming is something that you do once and that get used by multiple for many years You can visit him on his blog - Follow on twitter : @pranayamr

2 thoughts on “Find duplicate with Linq

  1. weber genesis silver

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