CSDN 中诸多初学者每每还是在问:如何从数据库加载自关联表数据,并显示到 TreeView 上?
因此,这里提供一个最简单的递归创建模型以供参考。
表模型
关于自关联模型的建立以及涉及的引用完整性约束,有多种策略。
为了简化,此示例中 ParentID=0 表示无实际的父节点。
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代码
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<%
@ Page Language="C#" %>
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<%
@ Import Namespace="System.Data" %>
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<%
@ Import Namespace="System.Data.OleDb" %>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<script runat="server">
protected void Page_Load(object sender, EventArgs e)
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{
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if (!IsPostBack)
{
CreateTreeView();
}
}
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/// <summary>
/// 创建 TreeView
/// 此方法采取一次性加载目标数据到 DataTable,递归查询 DataTable ,创建子节点
/// </summary>
private void CreateTreeView()
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{
//
const int VirtualRootId = 0; // 虚拟的根节点 ID, 表中 ParentID=0 的节点表示无实际父节点
const string SQL_SELECT = "SELECT NodeId, NodeName,ParentId FROM TreeView ORDER BY NodeId ASC";
//
string connStr = "Provider=Microsoft.Jet.OleDb.4.0;data source=" + Server.MapPath("DEMO15_TreeViewDemo.mdb"); ;
//
OleDbDataAdapter da = new OleDbDataAdapter(SQL_SELECT, connStr);
DataTable dt = new DataTable();
//
da.Fill(dt);
//
CreateTreeViewRecursive(treeMenu.Nodes, dt, 0);
}
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/// <summary>
/// 递归查询数据,创建 TreeNode 节点
/// </summary>
/// <param name="nodes"></param>
/// <param name="dataSource"></param>
/// <param name="parentId"></param>
private void CreateTreeViewRecursive(TreeNodeCollection nodes, DataTable dataSource, int parentId)
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{
//
string fliter = String.Format("ParentId={0}", parentId);
// 查询子节点
DataRow[] drArr = dataSource.Select(fliter);
TreeNode node;
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foreach(DataRow dr in drArr)
{
//
node = new TreeNode();
nodes.Add(node);
node.Text = (string)dr["NodeName"];
// 设置其他属性
//
// 递归创建子节点
CreateTreeViewRecursive(node.ChildNodes, dataSource, (int)dr["NodeId"]);
// 移除已添加行,提高性能
dataSource.Rows.Remove(dr);
}
}
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</script>
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<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ASP.NET DEMO15: CreateTreeViewResursiveFromDb</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h1>Menu Tree created from DataBase</h1>
<a href="http://www.cnblogs.com/Jinglecat/archive/2007/08/10/850090.html">More Details</a>
<hr />
<asp:TreeView ID="treeMenu" runat="server" ExpandDepth="1">
</asp:TreeView>
</div>
</form>
</body>
</html>
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版本信息ASP.NET 2.0
完整示例
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