C#在窗口中ComboBox控件中加载数据库数据

//窗口加载事件
        private void register_Load(object sender, EventArgs e)
        {

            bindPro();//绑定省份数据函数
         

        }
        /// <summary>
        /// 绑定省份数据函数
        /// </summary>
        public void bindPro()
        {
            //获取数据库数据
            List<ProvinceData> list = new ProvinceDA().Select();
            //添加到窗口中
            if (list != null)
            {
                foreach (ProvinceData data in list)
                {
                    comboPro.Items.Add(data.ProName);
                }
                comboPro.SelectedItem = comboPro.Items[0];
            }
        }

        public void bindCity()
        {
            comboCity.Items.Clear();
            //根据选取的省份获取省份编号
            string proName=comboPro.SelectedItem.ToString();
            string proCode = new ProvinceDA().SelectByProName(proName).ProCode;
            //根据选取的省份编号绑定城市数据
            List<CityData>list = new CityDA().SelectByProCode(proCode);
            if (list != null)
            {
                foreach (CityData data in list)
                {
                    comboCity.Items.Add(data.CityName);
                }
                comboCity.SelectedItem = comboCity.Items[0];
            }
        }

//根据选取省份的变化，变化城市
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            bindCity();
        }