对datatable筛选重复数据

string[] temp = null;
if (tb.Rows.Count > 0)
{
     //对重复的数据进行筛选
     Hashtable ht = new Hashtable();
     foreach (DataRow dr in tb.Rows)
     {
          string s = dr["originalName"];
          if (!ht.Contains(s))
              ht[s] = dr["originalName"];
     }
     temp = new string[ht.Count];
     ht.Keys.CopyTo(temp, 0);
}