前台代码:
<%@ Page Language="C#" CodeFile="DropDownListDemo.aspx.cs" Inherits="DropDownListDemo" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"></asp:DropDownList>
<asp:DropDownList ID="DropDownList2" runat="server"></asp:DropDownList>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
后台代码:
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 DropDownListDemo : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DropDownList1.AutoPostBack = true;
DropDownList2.AutoPostBack = true;
if (!IsPostBack)
{
DropDownList1.Items.Add("----请选择----");
DropDownList2.Items.Add("----请选择----");
BindDDL("SELECT 列名1,列名2 FROM 表名", DropDownList1);
DropDownList2.Enabled = false;
}
else if (DropDownList1.SelectedIndex == 0)
{
DropDownList2.Enabled = false;
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList2.Items.Clear();
DropDownList2.Items.Add("----请选择----");
if (DropDownList1.SelectedIndex == 0)
{
DropDownList2.Enabled = false;
}
else
{
DropDownList2.Enabled = true;
BindDDL("SELECT 列名1,列名2 FROM 表名 WHERE 条件1 = '" + DropDownList1.SelectedValue + "'", DropDownList2);
}
}
protected void BindDDL(string queryString, DropDownList ddl)
{
string connectionString = "Data Source=****;Initial Catalog=****;User ID=****;Password=****";
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand command = new SqlCommand(queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
ddl.Items.Add(new ListItem(reader[0].ToString(), reader[1].ToString()));
}
reader.Close();
}
}
}
原文地址：http://blog.sina.com.cn/s/blog_3d9600900100pg1i.html
再次感谢作者的分享。