关于 DropDownList_SelectedIndexChanged 的问题

Question

我想用两个 DropDownList_SelectedIndexChanged 控制一个时间  地一个里面输出 “学院”，当点击时会下拉出来学校的各个学院 比如“信息学院”，“经管学院”等，选中学院后 点击第二个DropDownList1_SelectedIndexChanged 其中会出现学院的专业  不如“计算机专业”，“软件专业”等  请大家指教  最好有源代码能连数据库就更好了  

Answer 1

无刷新的去百度搜吧有刷新的很简单dropdownlist1的autopostback设置为true
然后
在DropDownList1_SelectedIndexChanged事件里获取DropDownList1.selectValue然后去数据库中按照selectValue查询专业，然后绑定到dropDownList2上

Answer 2

   <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
               <asp:DropDownList ID="ddlLB" runat="server" Width="15%" AutoPostBack="True" OnSelectedIndexChanged="ddlLB_SelectedIndexChanged">
               </asp:DropDownList>
                 <asp:DropDownList ID="ddlChild" runat="server" Width="20%">
               </asp:DropDownList>
                 </ContentTemplate>
        </asp:UpdatePanel>
        </div> 
 protected void ddlLB_SelectedIndexChanged(object sender, EventArgs e)
    {
        if(this.ddlLB.SelectedValue!=null)
        {
            BindChild(this.ddlLB.SelectedValue);
        }
    }ddlLB.DataSource=ds;
ddlLB.DataValueField="id";
ddlLB.DataTextField="name";
ddlLB.DataBind();

Answer 3

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;public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ListItem[] list = new ListItem[] { 
                new ListItem("陕西","shanxi"), 
                new ListItem("河南","henan"),
                new ListItem("北京市","beijing")
            };
            DropDownList1.Items.AddRange(list);
        }
        GetCity();
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        GetCity();
    }    private void GetCity()
    {
        DropDownList2.Items.Clear();
        ListItem[] shanxi = new ListItem[] { new ListItem("咸阳"),new ListItem("西安"), new ListItem("渭南") };
        ListItem[] henan = new ListItem[] { new ListItem("郑州"), new ListItem("开封") };
        switch (DropDownList1.SelectedValue)
        {
            case "shanxi":
                DropDownList2.Items.AddRange(shanxi);
                break;
            case "henan":
                DropDownList2.Items.AddRange(henan);
                break;
            case "beijing":
                DropDownList2.Items.Add("北京市");
                break;
        }
    }
}