实验室/DropDownList.aspx.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;

public partial class DropDownList : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DLL2Bind();
            DLL3Bind();
            ProvinceBind();
            CityBind();
        }
    }

    private void DLL2Bind()
    {
        ListItem li1 = new ListItem("北京", "1");
        ListItem li2 = new ListItem("上海", "2");
        ListItem li3 = new ListItem("广州", "3");
        ListItem li4 = new ListItem("深圳", "4");
        ddl2.Items.Add(li1);
        ddl2.Items.Add(li2);
        ddl2.Items.Add(li3);
        ddl2.Items.Add(li4);
    }

    private void DLL3Bind()
    {
        List<City> list = new List<City>();
        City c1 = new City() { id = 1, name = "北京" };
        City c2 = new City() { id = 2, name = "上海" };
        City c3 = new City() { id = 3, name = "广州" };
        City c4 = new City() { id = 4, name = "深圳" };
        list.Add(c1);
        list.Add(c2);
        list.Add(c3);
        list.Add(c4);
        ddl3.DataTextField = "name";
        ddl3.DataValueField = "id";
        ddl3.DataSource = list;
        //WebForm数据源控件和WinForm数据源控件的区别，要加上下面这句话
        ddl3.DataBind();
    }

    #region 省市级联特效
    private void ProvinceBind()
    {
        List<ShengTable> list = new List<ShengTable>();
        SqlDataReader reader = DBHelper.ExecuteGetReader(System.Data.CommandType.Text, "select * from ShengTable", null);
        while (reader.Read())
        {
            ShengTable st = new ShengTable();
            st.proID = reader.GetInt32(0);