I have excel file with 290000 records and columns count is 19.
I read it in datatable.
I have to get all records that are duplicated in columns index 0,1,5,6,8,9,16.
I use in List:
IDList = dt.AsEnumarable.Select(function(row) row(0)+";"+row(1)+";"+…+row(16)).ToList()
IDDubl = IDList.Distinct().Where(function(item) IDList.LastIndexOf(item) <> IDList.IndexOf(item) ).ToList()
And then in for each I write comment in DT what is this double at each records in IDDubl
But it work very very long.
What other method can I use?