Activation User Registration

//Activation link

private string GetUserID(string p)
{
    SqlCommand cmd = new SqlCommand("SELECT User_id From Auction_user_regist WHERE Email=@Email", con);
        cmd.Parameters.AddWithValue("@Email", tbxEmail.Text);
         if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
            string User_id = Convert.ToString(cmd.ExecuteScalar());
            con.Close();
            cmd.Dispose();
            return User_id;
        }
    }


// is_approved code 

public partial class Account_is_approved : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnection"].ToString());
    SqlCommand cmd = new SqlCommand();
    string User_id,Email;

    protected void Page_Load(object sender, EventArgs e)
    {
           
if ((Request.QueryString["User_id"] != null) & (Request.QueryString["Email"] != null))
{
     User_id = Request.QueryString["User_id"];
     Email = Request.QueryString["Email"];
     SqlCommand cmd = new SqlCommand("UPDATE Auction_user_regist SET is_approved=1 WHERE User_id=@User_id AND Email=@Email", con);
     cmd.Parameters.AddWithValue("@User_id", User_id);
     cmd.Parameters.AddWithValue("@Email", Email);
     con.Open();
     cmd.ExecuteNonQuery();
     con.Close();
        }
    }
}