Treeview控件2.0与ACCESS数据库

OleDbConnection cn;
protected void Page_Load(object sender, EventArgs e)
{
cn = new OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0;Data Source=" + Server.MapPath("xxx.mdb"));
if (!IsPostBack)
{
BindTree();
}

}
private void BindTree()
{
int i =0;
int j =0;
DataSet dst = GetTreeViewData();
foreach (DataRow mRow in dst.Tables["province"].Rows)
{
TreeNode mNode = new TreeNode((string)mRow["Province"]);
mNode.ImageUrl = "../Images/folder.gif";
TreeView1.Nodes.Add(mNode);
foreach (DataRow cRow in mRow.GetChildRows("Children"))
{
TreeNode cNode = new TreeNode((string)cRow["City"]);
mNode.Expanded = false;
cNode.NavigateUrl = "TopicList.aspx?forumID=" + dst.Tables["city"].Rows[i][0].ToString();
cNode.ImageUrl = "../Images/page.gif";
j = j + 1;
mNode.ChildNodes.Add(cNode);
}
}
}
private DataSet GetTreeViewData()
{
OleDbDataAdapter daP = new OleDbDataAdapter("select * from ProvinceTB", cn);
OleDbDataAdapter daC = new OleDbDataAdapter("select * from CityTB", cn);
DataSet ds = new DataSet();
daP.Fill(ds, "province");
daC.Fill(ds, "city");
ds.Relations.Add("Children", ds.Tables["province"].Columns["PID"], ds.Tables["city"].Columns["PID"]);
return ds;
}