如何在ASP.NET另一个下拉列表过滤下拉列表中值，C＃ [英] How to filter dropdown list values by another dropdown list in ASP.NET, c#

问题描述

我对过滤器的简单问题。
我有4个下拉列表的筛选器从MySQL数据库表我的web应用程序的数据。
第一个下拉列表中已被选中显示只有一个PROJECT_ID但其他下拉列表显示数据库中的所有可能的值 - 这是我迄今所取得。

I have a simple question about filters. I have 4 dropdown lists which filter the data in my web application from MySQL database table. The first dropdown list is already selected showing only one project_id but the others drop down lists displays all the possible values from the database - this is what I made so far.

但我要选定特定的项目仅显示的数据值。

But I want to display only the data values for that particular project selected.

这是ASP.NET 4.0，C＃后面使用MySQL数据库。
任何帮助将AP preciated。
谢谢

It's ASP.NET 4.0, C# behind and MySQL database used. Any help will be appreciated. Thanks

推荐答案

检查以下用于填充级联下拉列表的链接。

check out following links for populating cascading drop down list.

<一个href=\"http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/CascadingDropDown/CascadingDropDown.aspx\" rel=\"nofollow\">http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/CascadingDropDown/CascadingDropDown.aspx

HTTP：//www.$c$cproject.com/KB/ ASPNET / CascadingDropDown.aspx

的http://www.aspsnippets.com/Articles/Creating-Cascading-DropDownLists-in-ASP.Net.aspx

code：

<table>
    <tr>
        <td>First</td>
        <td><asp:DropDownList ID="DDLFirst" runat="server"  AutoPostBack="true"
                onselectedindexchanged="DDLFirst_SelectedIndexChanged"></asp:DropDownList></td>
    </tr>
    <tr>
        <td>Secord</td>
        <td><asp:DropDownList ID="DDLSecond" runat="server" AutoPostBack="true"
                onselectedindexchanged="DDLSecond_SelectedIndexChanged">
            <asp:ListItem Text="Select" Value="Select"></asp:ListItem>    
            </asp:DropDownList></td>
    </tr>
    <tr>
        <td>Thrid</td>
        <td><asp:DropDownList ID="DDLThird" runat="server"><asp:ListItem Text="Select" Value="Select"></asp:ListItem>    </asp:DropDownList></td>
    </tr>
</table>

// code背后
        保护无效的Page_Load（对象发件人，EventArgs的发送）
        {
            如果（！的IsPostBack）
            {
                //你的code绑定的首次下降downlist

// Code behind protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { // your code to bind the first drop downlist

        }
    }

    protected void DDLFirst_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DDLFirst.SelectedIndex > 0)
        {
            string FirstDDLValue = DDLFirst.SelectedItem.Value;
            // below your code to get the second drop down list value filtered on first selection


        }

    }

    protected void DDLSecond_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DDLSecond.SelectedIndex > 0)
        {
            string SecondDDLValue = DDLSecond.SelectedItem.Value;
            // below your code to get the third drop down list value filtered on Second selection


        }
    }

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