本地缓存数据去重

 DataTable dt = new DataTable();
  dt = GetTavle();//给dt赋值
 DataView myDataView = new DataView(dt);
 string[] strComuns = { "s1" };//此处可加任意数据项组合
 dt = myDataView.ToTable(true, strComuns);
 DataTable dt_new = new DataTable();
dt_new =dt;