using System.Data.SqlClient;//SQl的程序集
       //connectionstring是连接数据库的字符串
SqlConnection coon = new SqlConnection(connectionstring);
            coon.Open();
            DataSet ds = new DataSet();
            SqlDataAdapter da = new SqlDataAdapter();
            SqlCommand cmd = new SqlCommand("select * from 酒店人员", coon);
            da.SelectCommand = cmd;
            da.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0];
            coon.Close();

------解决方案--------------------

treeView1.ShowLines = true;
           treeView1.ImageList = imageList1;//server=.;integrated security=sspi;database=db_02
           SqlConnection con = new SqlConnection("server=.;uid=sa;pwd=123;database=db_02");
           con.Open();
           SqlCommand com = new SqlCommand("select * from tb_07", con);
           SqlDataReader dr = com.ExecuteReader();
           TreeNode newNode1 = treeView1.Nodes.Add("A","商品信息",1,2);//一级节点
           while (dr.Read())
           {
               TreeNode newNode12 = new TreeNode("商品编号" + dr[1].ToString(),3,4);// 二级节点
               // 3表示没有单击节点时显示的图标索引值，
               newNode12.Nodes.Add("A","商品名称：" + dr[0].ToString(),5,6);
               newNode12.Nodes.Add("A","商品数量：" + dr[3].ToString(),7,8);
               newNode12.Nodes.Add("A", "商品价格：" + dr[2].ToString(),9,10);
               newNode1.Nodes.Add(newNode12);
         
           }
           dr.Close();
           con.Close();
           treeView1.ExpandAll();
       }

------解决方案--------------------

C# code
 private void bindTreeView1()
        {
            string sql = "select * from dm_category";
            DataTable dt = db.ExecuteDataTable(sql, CommandType.Text, null);
            DataRow[] dr = dt.Select("parent_id is null");
            for (int i = 0; i < dr.Length; i++)
            {
                TreeNode tn = new TreeNode();
                tn.Text = dr[i]["category_name"].ToString();
                tn.Tag = dr[i]["id"].ToString();
                    FillTree(tn, dt);
                treeView1.Nodes.Add(tn);
            }
        }

        private void FillTree(TreeNode node, DataTable dt)
        {
            DataRow[] drr = dt.Select("parent_id='" + node.Tag.ToString() + "'");
            if (drr.Length > 0)
            {
                for (int i = 0; i < drr.Length; i++)
                {
                    TreeNode tnn = new TreeNode();
                    tnn.Text = drr[i]["category_name"].ToString();
                    tnn.Tag = drr[i]["id"].ToString();
                    if (drr[i]["parent_id"].ToString() == node.Tag.ToString())
                    {
                        FillTree(tnn, dt);
                    }
                    node.Nodes.Add(tnn);
                }
            }
        }

 private void 删除节点ToolStripMenuItem_Click(object sender, EventArgs e)
  {
    
  treeView1.Nodes.Remove(treeView1.SelectedNode);
  N_conn.Open();
  string str = "delete from Ware where 名称='"+treeView1.SelectedNode.Text+"' ";
  SqlCommand cmd = new SqlCommand(str,N_conn);
  cmd.ExecuteNonQuery();
  N_conn.Close();

  }


treeview1.Nodes.Add(node);

------解决方案--------------------