private void 车位信息检索ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            panel1.Controls.Clear();
            this.IsMdiContainer = true;
            SearchParking searchParking = new SearchParking();

            searchParking.MdiParent = this;
            searchParking.Parent    = this.panel1;
            label1.Visible          = false;

            searchParking.FormBorderStyle = FormBorderStyle.None;
            searchParking.Show();
        }