利用ASP.NET DataGrid显示主次关系的数据
大家在实际工作中有没有遇到要在DataGrid中显示带有主次结构的数据呢？如果你对ADO.NET和SQL Server2000熟悉的话，我们下面就举一个利用VS.NET自带的示例数据库Northwind和VB.NET来说明如何实现这一目标。首先，我们先准备要显示的带有主次结构的数据。下面就是要绑定到HierarchicalDataGrid.aspx的VB.NET代码文件HierarchicalDataGrid.aspx.vb的内容：
Imports System.Data.SqlClient
Public Class HierarchicalDataGrid
Inherits System.Web.UI.PageProtected WithEvents DataGrid1 As System.Web.UI.WebControls.DataGrid#Region " Web Form Designer Generated Code "
'下面的调用对Web Form设计器来说是必须的
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()End Sub
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: 这个方法是为Web Form设计器调用的'不要用代码编辑器改变这里.InitializeComponent()End Sub#End Region
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'打开数据库连接
Dim OrdersConnection As New SqlConnection("Server=(local)\NetSDK;Database=northwind;Trusted_Connection=yes")'得到订单和订单详细信息
Dim OrderAdapter As New SqlDataAdapter("Select * from Orders; select OrderID ,Products.ProductName,[order Details].Unitprice,[order Details].Quantity,[order Details].discount from [order Details],Products where [Order Details].ProductId=Products.ProductID", OrdersConnection)'创建并填充DataSet对象
Dim OrderDataSet As New DataSet()OrderAdapter.Fill(OrderDataSet)
'设定表名字
OrderDataSet.Tables(0).TableName = "Orders"OrderDataSet.Tables(1).TableName = "Order Details"'在基于OrderID字段的两个表之间建立父子关系
Dim Parent As DataColumn = OrderDataSet.Tables("Orders").Columns("OrderID")Dim Child As DataColumn = OrderDataSet.Tables("Order Details").Columns("OrderID")Dim OrderRelation As DataRelation = New DataRelation("OrderRelation", Parent, Child, False)
'为DataSet添加关系
OrderDataSet.Relations.Add(OrderRelation)'把DataGrid绑定到Orders表
DataGrid1.DataSource = OrderDataSet.Tables("Orders").DefaultViewDataBind()End Sub
Private Sub DataGrid1_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DataGrid1.ItemDataBound
e.Item.Cells(0).BackColor = System.Drawing.Color.IvoryEnd SubEnd Class在HierarchicalDataGrid.aspx中，我们为DataGrid1建立模板列，并把另外一个DataGrid嵌入到这个模板列，父一级的DataGrid用来显示主记录，比如：订单。子一级DataGrid用来显示详细信息，比如：订单的详细信息。我们这样为子DataGrid动态指定数据源：
DataSource='<%# Ctype(Container.DataItem,DataRowView).CreateChildView("OrderRelation") %>'>
上面这句就是实现显示主次关系数据的关键。根据当前父一级记录，DataRowView.CreateChildView利用前面创建的关系的名字作为参数获得子记录，并把它绑定到子DataGrid上。
下面就是我们要显示的ASPX页面的代码，HierarchicalDataGrid.aspx：
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="HierarchicalDataGrid.aspx.vb" Inherits="HierarchicalDataGrid.HierarchicalDataGrid" %>
<%@ Import namespace="System.Data"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML><HEAD><title>显示主次关系数据的例子</title><meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0"><meta name="CODE_LANGUAGE" content="Visual Basic 7.0"><meta name="vs_defaultClientScript" content="JavaScript"><meta name="vs_targetSchema" content=""></HEAD><body><form id="FrmDataGrid" method="post" runat="server"><P align="center"><asp:DataGrid id="DataGrid1" BorderColor="#0099FF" runat="server" ShowHeader="False" Width="470px" CellPadding="0" CellSpacing="0" AutoGenerateColumns="False" BorderWidth="2px"><Columns><asp:TemplateColumn><ItemTemplate><TABLE cellSpacing="0" cellPadding="0" width="100%" border="0"><TR><TD bgColor="#FF6600"><B>订单号：<%# DataBinder.Eval(Container.DataItem, "OrderID") %></B></TD></TR><TR><TD align="right"><asp:DataGrid id=DataGrid2 runat="server" AutoGenerateColumns="False" BorderColor="#33FF33" DataKeyField="OrderID" DataSource='<%# Ctype(Container.DataItem,DataRowView).CreateChildView("OrderRelation") %>'><HeaderStyle Font-Bold="True" ForeColor="#CC0066" BackColor="#FFCCFF"></HeaderStyle><Columns><asp:BoundColumn Visible="False" DataField="OrderID" ReadOnly="True"></asp:BoundColumn><asp:TemplateColumn HeaderText="产品名称"><HeaderStyle Width="300px"></HeaderStyle><ItemTemplate><%# DataBinder.Eval(Container.DataItem, "ProductName") %></ItemTemplate></asp:TemplateColumn><asp:BoundColumn DataField="UnitPrice" HeaderText="单价"></asp:BoundColumn><asp:BoundColumn DataField="Quantity" HeaderText="数量"></asp:BoundColumn><asp:BoundColumn DataField="Discount" HeaderText="折扣"></asp:BoundColumn></Columns></asp:DataGrid></TD></TR></TABLE></ItemTemplate></asp:TemplateColumn></Columns></asp:DataGrid></P></form></body></HTML>