here iam using String.Join("",Row.Item("t1").ToString,Row.Item("t2").ToString,Row.Item("t3").ToString,Row.Item("t4").ToString)
is there any way to do this more efficiently using linq or anything
Welcome to the community
Try this in invoke code with dt as in/out argument
Dt.AsEnumerable.ToList.ForEach(sub(row) row("Unique Party") = String.Join("",Row.Item("t1").ToString,Row.Item("t2").ToString,Row.Item("t3").ToString,Row.Item("t4").ToString))
Or you can use a single assign as below
Dt.Columns("Unique Party").Expression = "[t1] + [t2] + [t3] + [t4]"
Cheers