如何将下拉列表绑定到另一个下拉列表 [英] how to bind the dropdown list to another dropdown list

问题描述

我有两个下拉列表，并且我想彼此绑定，例如，如果我在一个下拉列表中选择印度作为我的国家，则另一个应该显示印度的州，如果我在ddl中选择美国，则它应该显示状态美国
请帮助我

i have two drop down list and i want to bind each other like if i select India as my country in one dropdown list the another one should display the states of India and if i select U.S in ddl then it should display the states of U.S.
plz help me out

推荐答案

嗨
选中此选项将为您提供想法

Hi
Check this it will give you idea

DataClassesDataContext Db = new DataClassesDataContext();
   protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {
           var result = from x in Db.cates
                        select x;

           DropDownList1.DataSource = result;
           DropDownList1.DataTextField = "cate1";
           DropDownList1.DataValueField = "id";
           DropDownList1.DataBind();

           var resultItem = from x in Db.Items
                        select x;

           DropDownList2.DataSource = resultItem;
           DropDownList2.DataTextField = "Item_name";
           DropDownList2.DataValueField = "item_code";
           DropDownList2.DataBind();
       }
   }
   protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
   {
       var result = (from x in Db.Items
                    where x.item_code == Convert.ToInt32(DropDownList1.SelectedValue)
                    select x).Single();
//put here as much as u want to bind ddl but make sure u bind ddlist in Load first  then assign SelectedValue .

       DropDownList2.SelectedValue = result.item_code.ToString();

   }

<div>
      <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"

          onselectedindexchanged="DropDownList1_SelectedIndexChanged">
      </asp:DropDownList>
      <asp:DropDownList ID="DropDownList2" runat="server">
      </asp:DropDownList>

  </div>

在DropDownList1_SelectedIndexChanged事件中，您必须在此处编写代码.
最好的问候
M.Mitwalli

In DropDownList1_SelectedIndexChanged Event you have to write your code here .
Best Regards
M.Mitwalli

它被称为 Cascading Dropdown .

看这里:
CascadingDropDown演示 [使用SQL数据库的AJAX级联下拉示例 [ ^ ]
在选择ASP.NET上填充级联DropDownList [面向初学者的AJAX(第2部分)-使用XMLHttpRequest和jQuery AJAX实施级联下拉列表 [ ^ ]

It''s called Cascading Dropdown.

Look here:
CascadingDropDown Demonstration[^]
AJAX Cascading Dropdown Example using SQL Database[^]
Populate Cascading DropDownList On Selection ASP.NET[^]

If not update panels, then you need to use traditional AJAX - XMLHttpRequest.
Refer:
AJAX for beginners (Part 2) - Using XMLHttpRequest and jQuery AJAX to implement a cascading dropdown[^]

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