上一节我们已经知道DataGrid排序功能是由AllowSorting属性控制的，这一小节里，我们将通过实例来验证这个功能。
在DataCon Web项目里，添加一个窗体，命名为DataGrid_Sample4.aspx，添加一个DataGrid控件，DataGrid_Sample4.aspx的主要HTML代码如下：
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
<FONT face="宋体"></FONT>
<asp:DataGrid id="DataGrid1"
runat="server" PageSize =6
AllowPaging="True" AllowSorting="True" BorderColor="#009900" BorderWidth="1px" CellPadding="0">
<AlternatingItemStyle
Font-Size="X-Small" BackColor="WhiteSmoke"> </AlternatingItemStyle>
<ItemStyle Font-Size="X-Small" BackColor="#FFFFFF"> </ItemStyle>
<HeaderStyle Font-Size="X-Small" Font-Bold="True" BackColor="LightSteelBlue"></HeaderStyle>
<FooterStyle Wrap="False" BackColor="LightGray"></FooterStyle>
<PagerStyle Font-Size="X-Small" Font-Bold="True" Position="TopAndBottom" BackColor="Linen" Mode="NumericPages"></PagerStyle>
</asp:DataGrid>
</form>
</body>
DataGrid_Sample4.aspx.vb中的代码如下：
'----code begin----
'引入名称空间
Imports System
Imports System.Data
Imports System.Web.UI
Public Class DataGrid_Sample4_aspx
Inherits System.Web.UI.Page
#Region " Web 窗体设计器生成的代码 "
'此处省略了窗体设计器生成的代码，以节约篇幅
#End Region
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'使用viewstate("sort")来保存DataGrid排列数据的依据，初始化为id字段
viewstate("sort") = "id"
'调用数据绑定过程
getdata()
End Sub
'读取数据信息过程
Sub getdata()
Dim mycon As OleDb.OleDbConnection
Try
mycon = New OleDb.OleDbConnection("provider=microsoft.jet.oledb.4.0;data source=" + Server.MapPath(".") + "\StudentInfor.mdb")
Dim mycmd As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter("select * from student", mycon)
Dim dt As Data.DataSet = New Data.DataSet
mycmd.Fill(dt)
Dim dv As Data.DataView = New Data.DataView
'声明DataView类，并实例化
dv = dt.Tables(0).DefaultView
dv.Sort = viewstate("sort")
'指定DataView类的Sort值，这个值由viewstate("sort")传入
DataGrid1.DataSource = dv
'指定DataGrid1的数据源为DataView
DataGrid1.DataBind()
Catch ex As Exception
Response.Write("程序出现错误，信息描述如下：<br>" & ex.Message.ToString)
Finally
mycon.Close()
End Try
End Sub
'翻页事件过程
Private Sub DataGrid1_PageIndexChanged(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs) Handles DataGrid1.PageIndexChanged
DataGrid1.CurrentPageIndex = e.NewPageIndex
getdata()
End Sub
'请求排列顺序事件过程
Private Sub DataGrid1_SortCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles DataGrid1.SortCommand
viewstate("sort") = e.SortExpression.ToString
getdata()
End Sub
End Class
'-----code end ----------
保存编译后，运行效果如图9.9所示。
图9.9 DataGrid_Sample4.aspx运行结果
