Duplicate in Datatable

Question

How to Find Duplicate Recoreds in Colum 1 in a DataTable

Vinay Singh · Answer

hi try the below query SELECT name , email , COUNT (*) FROM users GROUP BY name , email HAVING COUNT (*) > 1 check detail http://stackoverflow.com/questions/2594829/finding-duplicate-values-in-a-sql-table http://stackoverflow.com/questions/2594829/finding-duplicate-values-in-a-sql-table http://stackoverflow.com/questions/4522431/find-duplicate-entries-in-a-column

Rajeesh Menoth · Answer

Hi, Example : DataTable dt = new DataTable(); dt.Columns.Add(); dt.Columns.Add(); dt.Columns.Add(); dt.Rows.Add(1, "Test1" , "Sample1" ); dt.Rows.Add(2, "Test2" , "Sample2" ); dt.Rows.Add(3, "Test3" , "Sample3" ); dt.Rows.Add(4, "Test4" , "Sample4" ); dt.Rows.Add(5, "Test5" , "Sample5" ); var duplicates = dt.AsEnumerable().GroupBy(r => r[0]).Where(gr => gr.Count() > 1).ToList(); Console.WriteLine( "Duplicate found: {0}" , duplicates.Any()); dt.Rows.Add(1, "Test6" , "Sample6" ); // Duplicate on 1 dt.Rows.Add(1, "Test6" , "Sample6" ); // Duplicate on 1 dt.Rows.Add(3, "Test6" , "Sample6" ); // Duplicate on 3 dt.Rows.Add(5, "Test6" , "Sample6" ); // Duplicate on 5 duplicates = dt.AsEnumerable().GroupBy(r => r[0]).Where(gr => gr.Count() > 1).ToList(); if (duplicates.Any()) Console.WriteLine( "Duplicate found for Classes: {0}" , String.Join( ", " , duplicates.Select(dupl => dupl.Key))); Console.ReadLine(); Reference : http://stackoverflow.com/questions/8939516/how-to-find-duplicate-record-using-linq-from-datatable