Winform 中实现省市联动效果

1，省的ID，Name直接定义成类，实例化后添加的到ComBox（DropDrownList）中，DisplayMember设置为ProName

2，绑定后SelectedIndex=0，显示绑定的第一个值

3，Configure中设置连接字符串，ConfigurationManager 中得到字符串的值

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlClient;

using System.Configuration;



namespace 省市联动

{

    public partial class 省市联动 : Form

    {

        public 省市联动()

        {

            InitializeComponent();

        }



        private void 省市联动_Load(object sender, EventArgs e)

        {

            BindPro();

            //显示第一个 Province

            cmbBoxPro.SelectedIndex = 0;

        }

        //省发生变化的时候的事件

        private void cmbBoxPro_SelectedIndexChanged(object sender, EventArgs e)

        {

            ProIDSeled();

            //显示第一个 City

            cmbCity.SelectedIndex = 0;

        }



        //获取所选取的省的ID

        protected void ProIDSeled()

        {

            //

            ProCity ProSeled = new ProCity();

            ProSeled = (ProCity)cmbBoxPro.SelectedItem;  //选中项是 PorCity 的实例 



            if (ProSeled != null)

            {

                int numProIDSeled = ProSeled.ProID;

                string strProName = ProSeled.ProName;



                //绑定之前先把数据清除

                cmbCity.Items.Clear();

                cmbCity.SelectedItem = null;

                BindCity(numProIDSeled);   //市也相应变化

                //MessageBox.Show(numProIDSeled.ToString());

            }

        }





        //绑定省

        protected void BindPro()

        {

            string strConn = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using (SqlConnection conn = new SqlConnection(strConn))

            {

                conn.Open();

                string strSelPro = "SELECT   proID, proName FROM  Province";

                using (SqlCommand sqlCmd = new SqlCommand(strSelPro, conn))

                {

                    using (SqlDataReader sdr = sqlCmd.ExecuteReader())

                    {

                        while (sdr.Read())

                        {

                            ProCity PCity = new ProCity();

                            int numProID = sdr.GetInt32(sdr.GetOrdinal("ProID"));

                            string strProName = sdr.GetValue(sdr.GetOrdinal("ProName")).ToString();

                            PCity.ProID = numProID;

                            PCity.ProName = strProName;

                            cmbBoxPro.Items.Add(PCity);   //控件添加的是类

                        }

                    }

                }

            }

        }



        //绑定市

        protected void BindCity(int proID)

        {

            string strConn = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using (SqlConnection conn = new SqlConnection(strConn))

            {

                conn.Open();

                string strSelPro = "SELECT   cityID, cityName, proID FROM city where proID=@proId ";

                SqlParameter sqlParaCity = new SqlParameter("proId", proID);

                using (SqlCommand sqlCmd = new SqlCommand(strSelPro, conn))

                {

                    sqlCmd.Parameters.Add(sqlParaCity);

                    using (SqlDataReader sdr = sqlCmd.ExecuteReader())

                    {

                        while (sdr.Read())

                        {

                            int numCityID = sdr.GetInt32(sdr.GetOrdinal("cityID"));

                            string strCityName = sdr.GetValue(sdr.GetOrdinal("cityName")).ToString();

                            cmbCity.Items.Add(strCityName);   //控件添加的是类



                            //参数清除

                            sqlCmd.Parameters.Clear();

                        }

                    }

                }

            }

        }



        //定义一个省市的类

        public class ProCity

        {

            private int proID;

            private string proName;

            public int ProID

            {

                get

                {

                    return proID;

                }

                set

                {

                    this.proID = value;

                }

            }

            public string ProName

            {

                get

                {

                    return this.proName;

                }

                set

                {

                    this.proName = value;

                }

            }

        }

    }

}

配置文件中的字符串 App.Config

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <connectionStrings>

    <add name="ConnStr" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DBProvince.mdf;Integrated Security=True;User Instance=True"/>

  </connectionStrings>

</configuration>