datagrid update的問題

private void Page_Load(object sender, System.EventArgs e) {
// 在這裡放置使用者程式碼以初始化網頁
//檢查session
Auth_check ac = new Auth_check();
string alert_str = ac.check_login(Session);
Response.Write(alert_str);
this.dbp = new DBprocess(Server.MapPath("../ag.mdb"));

this.dbp.dbconn.Open();
this.sql = "Select * From "+ this.tb_name;

if(!IsPostBack) {
DataGrid1.DataSource = dbp.GetDataTable(this.sql,dbp.dbconn,tb_name);
DataGrid1.DataBind();
}
this.dbp.dbconn.Close();

}