var qu = (from tt in table1.AsEnumerable() join ss in table2.AsEnumerable() on tt.Field<int>("UniqID") equals ss.Field<int>(" UniqID ") select new { FirstName = tt.Field<string>("ColumnsFName"), LastName = ss.Field<string>("ColumnsLName"), }).ToList(); Note:- Using Left join we should check null rows in the second table. If have null row it`s throw error without ...