情况：当在asp:DropDownLis点击选取其中的一个值来响应datalist的值。
<form id="form1" runat="server">
<div>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:examConnectionString2 %>" SelectCommand="SELECT * FROM [Students]"></asp:SqlDataSource>
//DropDownList连接SqlDataSource2
<asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="SqlDataSource2"
DataTextField="StudentName" DataValueField="StudentNo" AutoPostBack="True">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:examConnectionString %>"
SelectCommand="select sub.SubjectNo,SubjectName,sub.SubjectKind,sub.Credit,sc.Score from Subjects sub,Score sc where sc.StudentNo = @StudentNo and sc.SubjectNo=sub.SubjectNo">
<SelectParameters>
//通过SqlDataSource1连接DropDownList
<asp:ControlParameter ControlID="DropDownList1" DefaultValue="1" Name="StudentNo" PropertyName="SelectedValue"
Type="String" />
</SelectParameters>
</asp:SqlDataSource>
//datalist连接SqlDataSource1
<asp:DataList ID="DataList1" runat="server" DataSourceID="SqlDataSource1">
<HeaderTemplate>
<table id="tblist">
<tr>
<th>课程编号</th>
<th>课程名</th>
<th>课程类别</th>
<th>学分</th>
<th>成绩</th>
</tr>
</HeaderTemplate>
<ItemTemplate>
<tr>
<td>
<asp:Label ID="SubjectNoLabel" runat="server" Text=‘<%# Eval("SubjectNo") %>‘ />
</td>
<td>
<asp:Label ID="SubjectNameLabel" runat="server" Text=‘<%# Eval("SubjectName") %>‘ />
</td>
<td>
<asp:Label ID="SubjectKindLabel" runat="server" Text=‘<%# Eval("SubjectKind") %>‘ />
</td>
<td>
<asp:Label ID="CreditLabel" runat="server" Text=‘<%# Eval("Credit") %>‘ />
</td>
<td>
<asp:Label ID="ScoreLabel" runat="server" Text=‘<%# Eval("Score") %>‘ />
</td>
</tr>
</ItemTemplate>
<FooterTemplate></table></FooterTemplate>
</asp:DataList>
</div>
</form>
</body>
</html>
asp:DropDownList与asp:DataList的联合使用
原文：http://www.cnblogs.com/tandy/p/5447600.html