ASP.NET中使用DropDownList实现无刷新二级联动详细过程

 

Demo.sql

 1 create table Car(

 2     [id] int identity,

 3     [brand] varchar(50) not null,

 4     [type] varchar(50) not null

 5 )

 6 go

 7 

 8 insert into Car ([brand],[type])values('BMW','B'),('BMW','M'),('BMW','W'),

 9     ('BENZ','B'),('BENZ','E'),('BENZ','N'),('BENZ','Z'),

10     ('HONDA','H'),('HONDA','O'),('HONDA','N'),('HONDA','D'),('HONDA','A'),

11     ('TOYOTA','T'),('TOYOTA','O'),('TOYOTA','Y'),('TOYOTA','A')

 

Demo.aspx

 1         <asp:ScriptManager runat="server">

 2         </asp:ScriptManager>

 3         <asp:UpdatePanel runat="server">

 4             <ContentTemplate>

 5                 <asp:DropDownList ID="dropBrand" runat="server" OnSelectedIndexChanged="dropBrand_SelectedIndexChanged"

 6                     Width="200" AutoPostBack="True">

 7                 </asp:DropDownList>

 8                 <asp:DropDownList ID="dropType" runat="server" Width="200">

 9                 </asp:DropDownList>

10             </ContentTemplate>

11         </asp:UpdatePanel>

 

Demo.aspx.cs

 1         protected void Page_Load(object sender, EventArgs e)

 2         {

 3             if (!IsPostBack)

 4             {

 5                 BindDrop();

 6             }

 7         }

 8 

 9         private void BindDrop()

10         {

11             //将数据捆绑到下拉列表中

12             string sqlStr = "select distinct [brand] from Car";

13             DataTable dt = SqlHelper.ExecuteDataTable(sqlStr);

14             dropBrand.DataTextField = "brand"; //设置列表显示的字

15             dropBrand.DataValueField = "brand"; //设置列表提交后获得的字段，自己理解为隐藏绑定数据

16             dropBrand.DataSource = dt;

17             dropBrand.DataBind();

18             dropBrand.Items.Insert(0, new ListItem("请选择车子品牌", ""));//第一项中加入内容,重点是绑定后添加

19             dropType.Items.Insert(0, new ListItem("请选择车子品牌型号", ""));//第一项中加入内容,重点是绑定后添加      

20         }

21 

22         protected void dropBrand_SelectedIndexChanged(object sender, EventArgs e)

23         {

24             string sqlStr = "select * from Car where [brand]='" + dropBrand.SelectedValue + "'";//页面加载后dropBrand.DataValueField隐藏绑定的数据，后边根据它查询dropType要显现的数据

25             DataTable dt = SqlHelper.ExecuteDataTable(sqlStr);

26             dropType.DataTextField = "type"; //设置dropBrand事件SelectedIndexChanged改变后dropType列表显示的数据

27             dropType.DataValueField = "id";

28             dropType.DataSource = dt;

29             dropType.DataBind();

30         }

 

 参考原文：http://www.cnblogs.com/cqchai/archive/2011/05/28/2061378.html