Javascript 如何在SqlDataSource中将变量从jQuery传递到SelectCommand？

我正在尝试将变量从jQuery传递到dropdownlist中的SqlDataSource

首先，jQuery的变量从asp:dropdownlist_1获取值，然后将其保存在jQuery的变量中

下一步，我想将jquery的变量发送到dropdownlist_2中的SelectCommand。可能吗

如果你有一个好主意，如果你能把它分享给我，那将是莫大的荣幸

先谢谢你

这是我的ASPX标记：

<asp:DropDownList ID="DropDown_1" runat="server" CssClass="form-control" 
     DataSourceID="SqlDataSource_1" 
     DataTextField="field_1" DataValueField="field_2"></asp:DropDownList>                               
<asp:SqlDataSource ID="SqlDataSource_1" runat="server" 
     ConnectionString="<%$ ConnectionStrings:asrsDBConnectionString %>" 
     SelectCommand="SELECT * FROM [table_1]"></asp:SqlDataSource>

<asp:DropDownList ID="DropDown_2" runat="server" CssClass="form-control" 
     DataSourceID="SqlDataSource_2" DataTextField="field_1" 
     DataValueField="field_2"></asp:DropDownList>                               
<asp:SqlDataSource ID="SqlDataSource_2"unat="server" 
     ConnectionString="<%$ ConnectionStrings:asrsDBConnectionString %>" 
     SelectCommand="SELECT * FROM [table_2] WHERE [variable_from_jquery] = "value_JQ"></asp:SqlDataSource>

这是我从你的问题中得出的结论，但我不太确定这是否正确

您有两个下拉菜单，第一个选择值，第二个在选择状态中使用该值以获得所需的结果。。。如果是这种情况，那么我建议您不要使用jquery，而只使用C#和asp.net。此外，还有一个非常有用的DropDorwnList事件，名为OnSelectedIndexChanged，可用于轻松完成此操作

这就是它的工作原理，首先是aspx文件：

<!-- For the first drop down menu, as you have done above, creating a SqlDataSource with a SelectCommand that will get the data from your table (I am using a table called products as an example) -->
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
    ConnectionString="<%$ ConnectionStrings:asrsDBConnectionString %>" 
    ProviderName="<%$ ConnectionStrings:asrsDBConnectionString.ProviderName %>"
    SelectCommand = "Select * from products">
</asp:SqlDataSource>

<!-- For the first drop DropDownList make sure you create a DataValueField of the column you want to show as the values form your DropDownList. Also pay attention to the name of the OnSelectedIndexChanged which will be very important for the C# part. And remember to set AutoPostBack to true... like the code block bellow -->
<asp:DropDownList ID="DropDownList1" runat="server"
    DataSourceID="SqlDataSource1"
    DataValueField="ProductID" 
    OnSelectedIndexChanged ="DropDownList1_SelectedIndexChanged"
    AutoPostBack="true">
</asp:DropDownList>


<!-- Now for the second DropDownList create another SqlDataSource, however this time don't create a SelectCommand because it will be created in the C# file depending on what you selected on your first DropDownList-->
<asp:SqlDataSource ID="SqlDataSource2" runat="server"
    ConnectionString="<%$ ConnectionStrings:asrsDBConnectionString %>" 
    ProviderName="<%$ ConnectionStrings:asrsDBConnectionString.ProviderName %>">
</asp:SqlDataSource>

<!-- when creating the second DropDownList make sure the DataValueField is the column that you want as values -->
<asp:DropDownList ID="DropDownList2" runat="server"
    DataSourceID="SqlDataSource2"
    DataValueField="UnitPrice"
    AutoPostBack="true">
</asp:DropDownList>

希望这能有所帮助，将其复制到一个新文件中，看看它是否有效，只需确保更改select语句，因为我刚刚使用了上面的语句作为示例。
有可能通过jQuery设置一些（隐藏）输入，然后使用它。

但没有必要采用如此复杂的方法。应用接吻原则（保持简单愚蠢）。一切都可以在
.aspx
中以声明方式完成。像这样的

<%--AutoPostBack="true" is important here --%>
<asp:DropDownList runat="server" ID="lstCountry" DataSourceID="sqlCountry" 
    DataTextField="CountryName" DataValueField="CountryId" AutoPostBack="true">
</asp:DropDownList>
<asp:SqlDataSource runat="server" ConnectionString='<%$ConnectionStrings:MyCNN %>' ID="sqlCountry"
    SelectCommand="select CountryId,CountryName from dbo.Countries" />

<asp:DropDownList runat="server" ID="lstState" DataSourceID="sqlState" 
    DataTextField="StateName" DataValueField="StateId">
</asp:DropDownList>
<asp:SqlDataSource runat="server" ConnectionString='<%$ConnectionStrings:MyCNN %>' ID="sqlState"
    SelectCommand="select StateId,StateName from dbo.States where CountryId=@CountryId" >
    <SelectParameters>
        <%--Take parameter value from 1st dropdown --%>
        <asp:ControlParameter Name="CountryId" ControlID="lstCountry" 
            PropertyName="SelectedValue" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>



无需更多代码。
您可以使用控制参数直接引用下拉列表（无需jquery）。如果必须使用javascript变量，请在隐藏字段上设置值，然后根据链接到的示例将其用作控制参数。您的方法有效，但我们可以避免重新加载页面吗？当然可以。包装
asp:UpdatePanel
提供的代码。非常感谢Alex。你救了我一天！！很高兴它做到了：）
//create a new method inside your page class, right under the Page_Load if possible, so inside the page class but outside the Page_Load method. The name of the method is what you set the OnSelectedIndexChanged event to from the first dropdown list. Hence, DropDownList1_SelectedIndexChanged
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    //get the selected value like so:
    string item1 = this.DropDownList1.SelectedValue.ToString();

    //and now set the SelectCommand for SqlDataSource which is used for the 2nd dropdownlist and use the value to filter your table.
    SqlDataSource2.SelectCommand = "Select * from products where ProductID='" + item1 + "'";
    //DataBind is important!
    SqlDataSource2.DataBind();
}

<%--AutoPostBack="true" is important here --%>
<asp:DropDownList runat="server" ID="lstCountry" DataSourceID="sqlCountry" 
    DataTextField="CountryName" DataValueField="CountryId" AutoPostBack="true">
</asp:DropDownList>
<asp:SqlDataSource runat="server" ConnectionString='<%$ConnectionStrings:MyCNN %>' ID="sqlCountry"
    SelectCommand="select CountryId,CountryName from dbo.Countries" />

<asp:DropDownList runat="server" ID="lstState" DataSourceID="sqlState" 
    DataTextField="StateName" DataValueField="StateId">
</asp:DropDownList>
<asp:SqlDataSource runat="server" ConnectionString='<%$ConnectionStrings:MyCNN %>' ID="sqlState"
    SelectCommand="select StateId,StateName from dbo.States where CountryId=@CountryId" >
    <SelectParameters>
        <%--Take parameter value from 1st dropdown --%>
        <asp:ControlParameter Name="CountryId" ControlID="lstCountry" 
            PropertyName="SelectedValue" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>