public void adddpart(partclass p)
        {
            label1.Text = p.partname;
            label2.Text = p.price;
            label3.Text = p.part_id.ToString();
            MemoryStream mem = new MemoryStream(p.pic);

            mem.Seek(0, SeekOrigin.Begin);
            pictureBox1.Image = Image.FromStream(mem);
            label4.Text       = "part";
            label5.Text       = p.customer_id.ToString();
        }
        void partdb()
        {
            part.Clear();
            String        sql = "Data Source=DESKTOP-8TO2TNB;Initial Catalog=car_sales;Integrated Security=True";
            SqlConnection con = new SqlConnection(sql);

            con.Open();
            string        query  = "SELECT *FROM part_car where customerid is null";
            SqlCommand    cmd    = new SqlCommand(query, con);
            SqlDataReader reader = cmd.ExecuteReader();

            while (reader.Read())
            {
                partclass p = new partclass {
                    part_id     = reader.GetInt32(0),
                    partname    = reader.GetString(1),
                    type        = reader.GetString(2),
                    pic         = (byte[])reader["pictuer"],
                    price       = reader.GetString(4),
                    customer_id = xx
                };
                part.Add(p);
            }
        }