asp.net-省市县三级联动

事件SelectedIndexChanged

--用来实现三级联动的表

create table AddressInfo
(
 cityId int,
 cityName varchar(20),
 orderId int
)

-----------插入数据

go
insert into AddressInfo values(1,'重庆',0)
insert into AddressInfo values(2,'上海',0)
insert into AddressInfo values(3,'安徽',0)
insert into AddressInfo values(4,'沙坪坝',1)
insert into AddressInfo values(5,'渝北区',1)
insert into AddressInfo values(6,'巴南区',1)
insert into AddressInfo values(7,'杨浦区',2)
insert into AddressInfo values(8,'南汇区',2)
insert into AddressInfo values(9,'普陀区',2)
insert into AddressInfo values(10,'合肥市',3)
insert into AddressInfo values(11,'安庆市',3)
insert into AddressInfo values(12,'芜湖市',3)
insert into AddressInfo values(13,'上桥',4)
insert into AddressInfo values(14,'新桥',4)
insert into AddressInfo values(15,'龙兴',5)
insert into AddressInfo values(16,'石船',5)
insert into AddressInfo values(17,'巴南1',6)
insert into AddressInfo values(18,'巴南2',6)
insert into AddressInfo values(19,'杨浦区1',7)
insert into AddressInfo values(20,'杨浦区2',7)
insert into AddressInfo values(21,'南汇区1',8)
insert into AddressInfo values(22,'南汇区2',8)
insert into AddressInfo values(23,'普陀区1',9)
insert into AddressInfo values(24,'普陀区2',9)
insert into AddressInfo values(25,'肥西',10)
insert into AddressInfo values(26,'肥东',10)
insert into AddressInfo values(27,'枞阳县',11)
insert into AddressInfo values(28,'望江县',11)
insert into AddressInfo values(29,'芜湖1',12)
insert into AddressInfo values(30,'芜湖2',12)

--------代码--------------------------------

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data;

public partial class _Default : System.Web.UI.Page 
{
    Content city = new Content();
    DataTable dt = null;
   //在加载事件里初始化省
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string strSql = string.Format("select * from addressInfo where orderId={0}", 0);
            dt = city.Select(strSql);
            this.ddlCity.DataSource = dt;
            this.ddlCity.DataTextField = "cityName";
            this.ddlCity.DataValueField = "cityId";
            this.ddlCity.DataBind();
            ddlCity_SelectedIndexChanged(sender, e);          
        }
       
    }
 //SelectedIndexChanged事件，当选择省的时候，该干什么（这里解释当你选择省的时候，显示该省所对应的市）
    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (this.ddlCity.SelectedValue!=null)
        {
            string strSql = string.Format("select * from addressInfo where orderId={0}", this.ddlCity.SelectedValue);
            dt = city.Select(strSql);
            this.ddlQu.DataSource = dt;
            this.ddlQu.DataTextField = "cityName";
            this.ddlQu.DataValueField = "cityId";
            this.ddlQu.DataBind();
            ddlQu_SelectedIndexChanged(sender, e);
        }
        
    }
    protected void ddlQu_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (this.ddlQu.SelectedValue != null)
        {
            string strSql = string.Format("select * from addressInfo where orderId={0}", this.ddlQu.SelectedValue);
            dt = city.Select(strSql);
            this.ddlXian.DataSource = dt;
            this.ddlXian.DataTextField = "cityName";
            this.ddlXian.DataValueField = "cityId";
            this.ddlXian.DataBind();
        }
    }
 }

注：

这是在百度看到的一个回答，思路很清晰，简洁，原理就是利用AutoPostBack属性，点击绑定对应数据。缺点就是刷新,来回到数据库查询，绑定数据