Question

我正在尝试根据dropdownlistA中选择的categoryId更新我的dropdownlistB使用此代码：

<asp:DropDownList ID="DropDownListA" runat="server" DataSourceID="SqlDataSourceA" DataTextField="Description" DataValueField="Description" AutoPostBack="True"></asp:DropDownList>
<asp:DropDownList ID="DropDownListB" runat="server" DataSourceID="SqlDataSourceB" DataTextField="Title" DataValueField="Title"></asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSourceA" runat="server" ConnectionString="<%$ ConnectionStrings:MainDbConnectionString1 %>" SelectCommand="SELECT [Description] FROM [BookCategory]"></asp:SqlDataSource>
 <asp:SqlDataSource ID="SqlDataSourceB" runat="server" ConnectionString="<%$ ConnectionStrings:MainDbConnectionString1 %>" SelectCommand="SELECT [Title] FROM [BooksInfo] WHERE ([CategoryId] = @CId)">
     <SelectParameters>
         <asp:QueryStringParameter DefaultValue="" Name="CId" QueryStringField="SELECT [CategoryId] FROM [BookCategory]" Type="Int32" />
     </SelectParameters>
</asp:SqlDataSource>

我不熟悉在ASP.NET中使用SQL和查询，并且无法弄清楚我做错了什么，dropdownlistB保持空白。（DropdownlistA中的AutoPostBack = true，所以它应该更新？）

Answer 1

我认为您正在寻找的是asp:ControlParameter这样的

<asp:ControlParameter ControlID="DropDownListA" PropertyName="SelectedValue"
                                  Name="EmpID" Type="Int32" DefaultValue="0" />

因此查询基于 DropDownListA 的选择。

使用SQL查询更新dropDownList

1 个答案: