数据库
CREATE TABLE [dbo].[LinkAge01] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[name] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[LinkAge02] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[lID] [int] NOT NULL ,
[name] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL
) ON [PRIMARY]
GO
页面index.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="index.aspx.cs" Inherits="_index" %>
<html>
<head runat="server">
<title>LinkAgeTest.</title>
<script language="javascript">
//jb函数会根据不同的浏览器初始化个xmlhttp对象
function jb()
{
var A=null;
try
{
A=new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
try
{
A=new ActiveXObject("Microsoft.XMLHTTP");
}
catch(oc)
{
A=null
}
}
if ( !A && typeof XMLHttpRequest != "undefined" )
{
A=new XMLHttpRequest()
}
return A
}
//下面Go函数是父列表框改变的时候调用，参数是选择的条目
function Go()
{
var svalue = document.getElementById("ddl01").value;//得到选择框的下拉列表的value
var weburl = "index.aspx? />
</div>
</form>
</body>
</html>
类文件 index.cs
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class _index : System.Web.UI.Page
{
private SqlConnection con;
private SqlDataAdapter sda;
private SqlCommand cmd;
private DataSet ds;
private SqlDataReader sdr;
//数据库开连接字符串
public static String conStr = "server=.; database=Test; uid=sa; pwd=sa";
protected void Page_Load(object sender, EventArgs e)
{
try
{
if (!IsPostBack)
{
con = new SqlConnection(conStr);
sda = new SqlDataAdapter("select * from LinkAge01", con);
ds = new DataSet();
sda.Fill(ds, "LinkAge01");
ds.Tables["LinkAge01"].DefaultView.Sort = "id asc";
ddl01.DataSource = ds.Tables["LinkAge01"].DefaultView;
ddl01.DataValueField = "id";
ddl01.DataTextField = "name";
ddl01.DataBind();
}
Response.Write("Request.Form[ddl02]:" + Request.Form["ddl02"] + "<br />");
BindDrop();
}
catch (Exception ex)
{
Response.Write("error:" + ex.ToString());
}
}
protected void btnOk_Click(object sender, EventArgs e)
{
try
{
Response.Write(ddl01.Items[ddl01.SelectedIndex].Text + "<br/>");
Response.Write(ddl02.Items[ddl02.SelectedIndex].Text + "<br/>");
}
catch (Exception ex)
{
Response.Write("error:" + ex.ToString());
}
}
protected void BindDrop()
{
String str = Request.QueryString["id"];
String str1 = ddl01.Items[ddl01.SelectedIndex].Value;
Response.Write("str1=" + str1 + "<br/>");
String a = str + "abc";
if (str + "abc" != "abc")//如果str加个字符串!=原来的字符串则说明触发过ddlS的onchange事件
BindChild(str);//触发过ddlS的onchange事件
else
BindParent(str1);//第一次加载活刷新
}
protected void BindParent(String str1)
{
try
{
//如果是第一次请求或者是刷新这个页面则根据ddlS的值来选择
//把参数转化成int
int i = Convert.ToInt32(str1);
ddl02.Items.Clear();
ddl02.Items.Add(new ListItem("请选择", "0"));
con = new SqlConnection(conStr);
cmd = new SqlCommand("select * from LinkAge02 where lID=" + i, con);
con.Open();
sdr = cmd.ExecuteReader();
while (sdr.Read())
{
ddl02.Items.Add(new ListItem(sdr["name"].ToString(), sdr["id"].ToString()));
}
sdr.Close();
con.Close();
ddl02.Items[0].Selected=true;
ddl01.Items[0].Selected = false;
//添加下面这话的意思是当点提交按钮提交窗体的时候第二个ddl02的状态能够得到保存
Response.Write("Request.Form[ddl02]:"+Request.Form["ddl02"]+"<br />");
ddl02.Value = Request.Form["ddl02"];
}
catch (Exception ex)
{
Response.Write("error:" + ex.ToString());
}
}
protected void BindChild(String str)
{
//通过js给包括dropdownlist任何控件添加的内容不会被保存状态
//把参数转化成int
int i = Convert.ToInt32(str);
String result = "";
Response.Clear();
con = new SqlConnection(conStr);
cmd = new SqlCommand("select * from LinkAge02 where lID=" + i, con);
con.Open();
sdr = cmd.ExecuteReader();
while (sdr.Read())
{
result += "," + sdr["name"].ToString() + "|" + sdr["id"].ToString();
}
sdr.Close();
con.Close();
Response.Write(result);
Response.Flush();
Response.Close();
}
}
原文地址：http://blog.csdn.net/mathew3625/archive/2008/04/13/2288707.aspx