The DataSet object represents an in-memory database
A single DataSet can contain one or many DataTable objects. You can define parent/child relationships between the DataTable objects contained in a DataSet. <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.SqlClient" %> <%@ Import Namespace="System.Web.Configuration" %> "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> void Page_Load() { if (!Page.IsPostBack) BuildTree(); } void BuildTree() { string connectionString = WebConfigurationManager.ConnectionStrings["Products"].ConnectionString; SqlConnection con = new SqlConnection(connectionString); SqlDataAdapter dadCategories = new SqlDataAdapter("SELECT Id,Name FROM ProductCategories", con); SqlDataAdapter dadProducts = new SqlDataAdapter("SELECT Title,CategoryId FROM Products", con); DataSet dstProducts = new DataSet(); using (con) { con.Open(); dadCategories.Fill(dstProducts, "Categories"); dadProducts.Fill(dstProducts, "Products"); } dstProducts.Relations.Add("Children", dstProducts.Tables["Categories"].Columns["Id"], dstProducts.Tables["Products"].Columns["CategoryId"]); foreach (DataRow categoryRow in dstProducts.Tables["Categories"].Rows) { string name = (string)categoryRow["Name"]; TreeNode catNode = new TreeNode(name); TreeView1.Nodes.Add(catNode); DataRow[] productRows = categoryRow.GetChildRows("Children"); foreach (DataRow productRow in productRows) { string title = (string)productRow["Title"]; TreeNode productNode = new TreeNode(title); catNode.ChildNodes.Add(productNode); } } }