datalist循环判断显示隐藏
大家好！我是新手，请教一个问题：
datalist中有一个循环输出的项是日期，还有一个项是主题，输出后得到
日期1
主题1
日期2
主题2
日期3
主题3
我想得到的结果是，如果日期1和日期2是同一天，则只显示日期1，日期2隐藏，效果如下：
日期1
主题1
主题2
日期3
主题3
我想这里有一个循环判断的问题，应该怎样写VB语句呢，谢谢大家！
[解决办法]
下面是一个例子。希望你能看明白
<%@ Page Language="VB" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><script runat="server"> Protected Sub Page_Load(sender As Object, e As EventArgs) If Not Page.IsPostBack Then Dim ds As New System.Data.DataSet() Dim dataTable1 As New System.Data.DataTable("BlogUser") Dim dr As System.Data.DataRow dataTable1.Columns.Add(New System.Data.DataColumn("UserId", GetType(System.Int32))) dataTable1.Columns.Add(New System.Data.DataColumn("UserName", GetType(System.String))) dataTable1.Columns.Add(New System.Data.DataColumn("riqi", GetType(System.DateTime))) dr = dataTable1.Rows.Add(New [Object]() {1, "【孟子E章】" + 1.ToString(), DateTime.ParseExact("2011-12-12", "yyyy-MM-dd", Nothing)}) dr = dataTable1.Rows.Add(New [Object]() {2, "【孟子E章】" + 2.ToString(), DateTime.ParseExact("2011-12-12", "yyyy-MM-dd", Nothing)}) dr = dataTable1.Rows.Add(New [Object]() {3, "【孟子E章】" + 3.ToString(), DateTime.ParseExact("2012-12-11", "yyyy-MM-dd", Nothing)}) dr = dataTable1.Rows.Add(New [Object]() {4, "【孟子E章】" + 4.ToString(), DateTime.ParseExact("2012-12-12", "yyyy-MM-dd", Nothing)}) dr = dataTable1.Rows.Add(New [Object]() {5, "【孟子E章】" + 5.ToString(), DateTime.ParseExact("2012-12-12", "yyyy-MM-dd", Nothing)}) DataList1.DataSource = dataTable1 DataList1.DataBind() End If End Sub Private LastDate As DateTime = DateTime.Now.AddYears(-100) Protected Sub DataList1_ItemDataBound(sender As Object, e As DataListItemEventArgs) If e.Item.ItemType = ListItemType.AlternatingItem Or e.Item.ItemType = ListItemType.Item Then Dim riqi As DateTime = DirectCast(DataBinder.Eval(e.Item.DataItem, "riqi"), DateTime) If LastDate = riqi Then Dim Panel1 As Panel = TryCast(e.Item.FindControl("Panel1"), Panel) Panel1.Visible = False End If LastDate = riqi End If End Sub</script><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title></title></head><body> <form id="form1" runat="server"> <asp:DataList ID="DataList1" runat="server" RepeatColumns="1" RepeatDirection="Vertical" RepeatLayout="Flow" OnItemDataBound="DataList1_ItemDataBound"> <ItemTemplate> <asp:Panel ID="Panel1" runat="server"> <%# Eval("riqi")%><br> </asp:Panel> <%# Eval("UserName")%><br> <br> </ItemTemplate> </asp:DataList> </form></body></html>