Linq和DataTable与DropDownList绑定的问题

Question

ddlcity2.Items.Clear();
        DataTable dt = new DataTable();
        DataColumn dc = new DataColumn("City");
        dt.Columns.Add(dc);
        DataColumn dcc = new DataColumn("ID");
        dt.Columns.Add(dcc);
        DataColumn dcx = new DataColumn("PK");
        dt.Columns.Add(dcx);
        DataRow dr = dt.NewRow();
        dr["City"] = "哈尔滨";
        dr["ID"] = "1";
        dr["PK"] = "1";
        dt.Rows.Add(dr);
        dr = dt.NewRow();
        dr["City"] = "牡丹江";
        dr["ID"] = "2";
        dr["PK"] = "1" ;
        dt.Rows.Add(dr);
        dr = dt.NewRow();
        dr["City"] = "北京";
        dr["ID"] = "3";
        dr["PK"] = "2";
        dt.Rows.Add(dr);
        关键的就在这里了
       ddlcity2.DataTextField = "City";
        ddlcity2.DataValueField = "PK";
        ddlcity2.DataSource = dt; //想让DropDownList有条件的绑定，在这里就是想利用Linq绑定条件是dr["PK"]="2"的数据     ddlcity2.DataBind();

Answer 1

ddlcity2.DataSource = dt.AsEnumerable().Where(p=>p.Field<string>("PK")=="2"); 
ddlcity2.DataBind();

Answer 2

ddlcity2.DataSource = dt.AsEnumerable().Where(p=> !string.IsNullOrEmpty(p.Field<string>("PK")) && p.Field<string>("PK")=="2");
 ddlcity2.DataBind();谢谢1L