linq 判断datatable重复键值

 private void CheckKey(DataTable dt ,string key)
        {
              DataTable m_tData = dt;
              var qt = m_tData.AsEnumerable().
                GroupBy(p => p[key]).
                Where(p => p.Count() > 1).
                Select(p => new { key = p.Key, value = p.Count() }).ToList();
                     foreach (var t in qt)
                {
                    Console.WriteLine("键值:{0} 重复次数:{1}", t.key, t.value);

                }
   }