做asp.net登录验证时的问题
public partial class WEB_DL : System.Web.UI.Page
{
    private string connectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void ImageButton2_Click(object sender, ImageClickEventArgs e)
    {
       
       

        SqlConnection con = new SqlConnection(connectionString);
        string selectSQL = "SELECT UserName,UserPD,QX FROM Table_User WHERE UserName='" + TextBox1.Text.Trim() + "'AND UserPD='" + TextBox2.Text.Trim() + "'";
        SqlCommand cmd = new SqlCommand(selectSQL, con);

        try
        {
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                if (reader["QX"].ToString() == "1")
                {
                    Response.Redirect("Admin.aspx");
                }
                else
                {
                    Session["username"] = reader["Name"].ToString();
                    Response.Redirect("Default.aspx");
                }
            }
            else
            {
                Label1.Visible = true;
            }
            reader.Close();
        }
        catch (Exception ee)
        {
            Response.Write(ee.Message);
        }
        finally
   &