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

转载于:https://www.cnblogs.com/Tench/p/4201621.html

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