DropDownList控件的使用方法

        <asp:DropDownList ID="DropDownList1" runat="server">
        </asp:DropDownList>
       
//1.1使用代码添加数据
        ListItem item = new ListItem(".net","1");
        this.DropDownList1.Items.Add(item);
        item = new ListItem("java", "2");
        this.DropDownList1.Items.Add(item);
        item = new ListItem("php", "3");
        this.DropDownList1.Items.Add(item);
        item = new ListItem("选择全部", "0");
        this.DropDownList1.Items.Insert(0, item);//在第一个索引处添加‘选择全部’选项

        <asp:DropDownList ID="DropDownList2" runat="server">
        </asp:DropDownList>
 
//2.1使用代码绑定数据源
        CategoriesManager manager = new CategoriesManager();
        this.DropDownList2.DataSource=manager.GetDataTable();
        this.DropDownList2.DataTextField = "name";
        this.DropDownList2.DataValueField = "id";
        this.DropDownList2.DataBind();
        this.DropDownList2.Items.Insert(0,new ListItem("选择全部", "0"));

        <asp:DropDownList ID="DropDownList3" runat="server" 
            DataSourceID="SqlDataSource1" DataTextField="Name" DataValueField="Id">
        </asp:DropDownList>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:BookShopConnectionString %>" 
            SelectCommand="SELECT [Id], [Name] FROM [Categories]"></asp:SqlDataSource>