我有一个复杂的项目，需要在列表视图中填充下拉列表。我能做到的。但是，当我从下拉列表中选择正确的值后单击更新时，它会在列表视图中返回一个空白值。我附上了一个示例代码，其中“日”来自一个拉自己，具体取决于月份。
那里的任何人都可以编辑我的代码以使其正常工作。从我所做的研究来看，我认为这与 Selected Index 的变化有关。
我正在使用visual web developer 2010 express 我也在使用framework 3.5
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:SqlDataSource ID="SqlDataSource2" runat="server"
ConnectionString="<%$ ConnectionStrings:DispatchConnectionString %>"
SelectCommand="SELECT [day] FROM [TMP]"></asp:SqlDataSource>
</div>
<asp:ListView ID="ListView1" runat="server" DataKeyNames="month"
DataSourceID="SqlDataSource1" InsertItemPosition="LastItem">
<AlternatingItemTemplate>
<tr style="">
<td>
<asp:Button ID="DeleteButton" runat="server" CommandName="Delete"
Text="Delete" />
<asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
</td>
<td>
<asp:Label ID="monthLabel" runat="server" Text='<%# Eval("month") %>' />
</td>
<td>
<asp:Label ID="dayLabel" runat="server" Text='<%# Eval("day") %>' />
</td>
</tr>
</AlternatingItemTemplate>
<EditItemTemplate>
<tr style="">
<td>
<asp:Button ID="UpdateButton" runat="server" CommandName="Update"
Text="Update" />
<asp:Button ID="CancelButton" runat="server" CommandName="Cancel"
Text="Cancel" />
</td>
<td>
<asp:Label ID="monthLabel1" runat="server" Text='<%# Eval("month") %>' />
</td>
<td>
<%--<asp:TextBox ID="dayTextBox" runat="server" Text='<%# Bind("day") %>' />--%>
<asp:DropDownList ID="list" runat="server" DataSourceID="SqlDataSource2"
DataTextField="day" DataValueField="day">
</asp:DropDownList>
</td>
</tr>
</EditItemTemplate>
<EmptyDataTemplate>
<table runat="server" style="">
<tr>
<td>
No data was returned.</td>
</tr>
</table>
</EmptyDataTemplate>
<InsertItemTemplate>
<tr style="">
<td>
<asp:Button ID="InsertButton" runat="server" CommandName="Insert"
Text="Insert" />
<asp:Button ID="CancelButton" runat="server" CommandName="Cancel"
Text="Clear" />
</td>
<td>
<asp:TextBox ID="monthTextBox" runat="server" Text='<%# Bind("month") %>' />
</td>
<td>
<asp:TextBox ID="dayTextBox" runat="server" Text='<%# Bind("day") %>' />
</td>
</tr>
</InsertItemTemplate>
<ItemTemplate>
<tr style="">
<td>
<asp:Button ID="DeleteButton" runat="server" CommandName="Delete"
Text="Delete" />
<asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
</td>
<td>
<asp:Label ID="monthLabel" runat="server" Text='<%# Eval("month") %>' />
</td>
<td>
<asp:Label ID="dayLabel" runat="server" Text='<%# Eval("day") %>' />
</td>
</tr>
</ItemTemplate>
<LayoutTemplate>
<table runat="server">
<tr runat="server">
<td runat="server">
<table ID="itemPlaceholderContainer" runat="server" border="0" style="">
<tr runat="server" style="">
<th runat="server">
</th>
<th runat="server">
month</th>
<th runat="server">
day</th>
</tr>
<tr ID="itemPlaceholder" runat="server">
</tr>
</table>
</td>
</tr>
<tr runat="server">
<td runat="server" style="">
</td>
</tr>
</table>
</LayoutTemplate>
<SelectedItemTemplate>
<tr style="">
<td>
<asp:Button ID="DeleteButton" runat="server" CommandName="Delete"
Text="Delete" />
<asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
</td>
<td>
<asp:Label ID="monthLabel" runat="server" Text='<%# Eval("month") %>' />
</td>
<td>
<asp:Label ID="dayLabel" runat="server" Text='<%# Eval("day") %>' />
</td>
</tr>
</SelectedItemTemplate>
</asp:ListView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:DispatchConnectionString %>"
DeleteCommand="DELETE FROM [TMP] WHERE [month] = @month"
InsertCommand="INSERT INTO [TMP] ([month], [day]) VALUES (@month, @day)"
SelectCommand="SELECT * FROM [TMP]"
UpdateCommand="UPDATE [TMP] SET [day] = @day WHERE [month] = @month">
<DeleteParameters>
<asp:Parameter Name="month" Type="String" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="month" Type="String" />
<asp:Parameter Name="day" Type="String" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="day" Type="String" />
<asp:Parameter Name="month" Type="String" />
</UpdateParameters>
</asp:SqlDataSource>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
//using System.Web.UI.WebControls.button;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
}