自建List<>绑定ComboBox下拉框实现省市联动

来源：互联网发布：不喝牛奶知乎编辑：程序博客网时间：2024/04/30 08:32
 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;namespace _04省市联动{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void Form1_Load(object sender, EventArgs e)        {            //所有的省份显示到第一个下拉框中            LoadAreaByAreaPid(0);//参数是列名AreaId的值        }        private void LoadAreaByAreaPid(int p)//参数p是列名AreaId的值        {            List<Area> list = new List<Area>();            list.Add(new Area() { AreaId = -1, AreaName = "请选择" });            string sql = "select AreaId,AreaName from TblArea where AreaPId=" + p;//参数p是列名AreaId的值            using (SqlDataReader reader = SqlHelper.ExecuteReader(sql))            {                if (reader.HasRows)                {                    while (reader.Read())                    {                        Area a = new Area();                        a.AreaId = Convert.ToInt32(reader["AreaId"]);                        a.AreaName = reader["AreaName"].ToString();                        list.Add(a);                    }                }            }            cmbSheng.DataSource = list;//绑定数据源            cmbSheng.DisplayMember = "AreaName";//主要是设置下拉框显示的值            cmbSheng.ValueMember = "AreaId";//实际值        }        private void cmbSheng_SelectedIndexChanged(object sender, EventArgs e)        {            if (cmbSheng.SelectedIndex!=0)            {                cmbCheng.Items.Clear();//清空                //获取当前选中的省份的id                int id = Convert.ToInt32(cmbSheng.SelectedValue);                string sql = "select AreaId,AreaName from TblArea where AreaPId=" + id;                using (SqlDataReader reader = SqlHelper.ExecuteReader(sql))                {                    if (reader.HasRows)                    {                        while (reader.Read())//练习                        {                            Area a = new Area();                            a.AreaId = Convert.ToInt32(reader["AreaId"]);                            a.AreaName = reader["AreaName"].ToString();                            cmbCheng.Items.Add(a);//自带集合，要重写ToString()方法                        }                    }                }            }        }    }}
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