C# automatic shows button disabled if seat already reserved

SqlConnection con = new SqlConnection("Data Source=(localdb)\\MSSQLLocalDB;Initial Catalog=LocalDB;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False");
            SqlCommand cmd = new SqlCommand("SELECT seatNumber FROM CustomersInfo WHERE seatNumber=@seatNumber",con);
            cmd.Parameters.AddWithValue("@seatNumber", textBox1.Text.ToLower());
            con.Open();
            SqlDataReader dr = cmd.ExecuteReader();

            if (dr.HasRows)
            {
                //if the seatNumber already exists.
                button2.Enabled = false;
                button2.BackColor = Color.Red;
            }
            else
            {
                //else
            }