Question

我有一个下拉列表列表，说A，B，C，D。所有A，B，C从同一个表（table1）中提取数据。 D从另一个中拉出（table2，但也会在sql查询中使用table1）。我想要实现的是，一旦从A下拉一个值，则自动选择B，C，D的值。我当前的asp代码只能在选择Dropdown A的随机值时才能生成，B，C可以自动选择值，但不能选择D.第二次选择A的随机值时，所有B，C，D得到值选择。

我的代码如下：一个

            <asp:DropDownList ID="DropDownListA" class="ddStyle" runat="server" DataSourceID="SqlDataSource2" DataTextField="country" DataValueField="country" AppendDataBoundItems="true" AutoPostBack="True" EnableViewState="true" ViewStateMode="Enabled">
                       <asp:ListItem Text="--Select One--" Value="" Selected="True" />  </asp:DropDownList>
    <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="select distinct country from table1 order by country"></asp:SqlDataSource>

乙

  <asp:DropDownList ID="DropDownList2" class="ddStyle" runat="server" DataSourceID="SqlDataSource1" DataTextField="GICS" DataValueField="GICS" AutoPostBack="True"></asp:DropDownList>
                        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="select distinct GICS, country from table1 where country=@country">
                            <SelectParameters>
                                <asp:ControlParameter ControlID="DropDownListA" Name="country" PropertyName="SelectedValue" />
                            </SelectParameters>
                        </asp:SqlDataSource>

C

  <asp:DropDownList ID="DropDownListC" class="ddStyle" runat="server" DataSourceID="SqlDataSource3" DataTextField="company" DataValueField="id" AutoPostBack="True"></asp:DropDownList>
                            <asp:SqlDataSource ID="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="select company, GICS, country, id from table1 where gics=@gics and country=@country">
                                <SelectParameters>
                                    <asp:ControlParameter ControlID="DropDownListB" Name="gics" PropertyName="SelectedValue" />
                                     <asp:ControlParameter ControlID="DropDownListA" Name="Country" PropertyName="SelectedValue" />
                                </SelectParameters>
                            </asp:SqlDataSource>

d

                            <asp:SqlDataSource ID="SqlDataSource5" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="select edition, company, id from table2 where table2.company in (select company from table1 where table1.id=@id)">
                                <SelectParameters>
                                    <asp:ControlParameter ControlID="DropDownListC" Name="id" PropertyName="SelectedValue" />
                                </SelectParameters>
                            </asp:SqlDataSource>
                            <asp:SqlDataSource ID="SqlDataSource4" runat="server"></asp:SqlDataSource>

我想知道如果从A下拉一个值后如何实现，那么B，C，D的值是自动选择的（我猜D首先选择的原因是由于它的sql查询）。谢谢你的建议！

asp.net下拉列表回发

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