DataTable高效判断是否存在重复的数据

private void CheckDataRepeat(DataSet dataSet, out string message)  
       {  
           message = string.Empty;  
           DataView dv = new DataView(dataSet.Tables[0]);  
           DataTable dtBmzd = null;  
           dtBmzd = dv.ToTable(true, new string[] { "列名1", "列名2" });  
           if (dtBmzd.Rows.Count < dataSet.Tables[0].Rows.Count)  
           {  
               message += "【列名1】、【列名2】值必须唯一，Excel中存在重复的数据，请确认！\n";  
           }  
       }