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