1、 (数据库设计如上)

2、代码：       

        private void SetArea()

        {

            DataTable dt = new DataTable();

            dt = customer.GetArea();

            DataView dv = dt.DefaultView;

            DataTable dtProvince = dv.ToTable(true, "province", "provinceid");

            for (int i = 0; i < dtProvince.Rows.Count; i++)

            {

                TreeNode nd = new TreeNode();

                nd.Tag = dtProvince.Rows[i]["provinceid"].ToString();

                nd.Text = dtProvince.Rows[i]["province"].ToString();

                TreeArea.Nodes.Add(nd);

                //插入子节点

                CreateTreeNode(ref nd, dt);

                TreeArea.ExpandAll();

                TreeArea.CheckBoxes = true;

            }

        }

        private void CreateTreeNode(ref TreeNode tnParent, DataTable dt)

        {

            DataRow[] drArr = dt.Select("provinceid = '" + tnParent.Tag + "'");

            if (drArr.Length == 0) return;

            for (int i = 0; i < drArr.Length; i++)

            {

                DataRow row = drArr[i];

                TreeNode nd = new TreeNode();

                nd.Tag = row["purchaseid"].ToString();

                nd.Text = row["areaname"].ToString();

                tnParent.Nodes.Add(nd);

                CreateTreeNode(ref nd, dt);

            }

        }

3、运行结果：