c#用最简单的方法构造树

private void Form1_Load(object sender, EventArgs e)

{

file_table();

creat_tree("产品列表");

}

System.Data.DataSet ds = new DataSet();

void file_table()

{

System.Data.Odbc.OdbcConnection myconn = new System.Data.Odbc.OdbcConnection(strtest);

myconn.Open();

System.Data.Odbc.OdbcCommand mycomm = new System.Data.Odbc.OdbcCommand();

mycomm.Connection = myconn;

mycomm.CommandText = "select label_id, label_name,label_root_id from label ";

System.Data.Odbc.OdbcDataAdapter adp = new System.Data.Odbc.OdbcDataAdapter();

adp.SelectCommand = mycomm;

adp.Fill(ds, "tree_table");

}

void creat_tree(string root)

{

TreeNode tnNew = treeView.Nodes[root];

tnNew.Tag = 0;

read_treenode(tnNew);

}

void read_treenode( TreeNode tnParent)

{

TreeNode tnNew = null;

foreach (DataRow dr in ds.Tables["tree_table"].Rows)

{

if (dr["label_root_id"].ToString() == tnParent.Tag.ToString())

{

tnNew = tnParent.Nodes.Add(dr["label_name"].ToString(), dr["label_name"].ToString());

tnNew.Tag = dr["label_id"].ToString();

read_treenode( tnNew);

}