lamda表示式寫法
dt = datado.SelectDalMeath(sqlStr.ToString());
var x = (from r in dt.AsEnumerable()
select r["newcode"]).Distinct().ToList();
newcode = x.Aggregate(newcode, (current, t) => current + (t.ToString() + ","));
string param = "city=" + city + "&projcodes=" + newcode;