BackTerminal.frmCatMan.btnAddCategory_Click C# (CSharp) Method

        private void btnAddCategory_Click(object sender, EventArgs e)
        {
            if (!TreeViewSelected()) return;
            frmCatNew form = new frmCatNew();
            form.ShowDialog();

            string title = form.result;
            if (title == null) return;

            string parentTitle = tvCategory.SelectedNode.Text;
            string str;
            Console.Out.Write(parentTitle);
            if (parentTitle == root)
            {
                str = "INSERT INTO dbo.category (title, parent_id) VALUES('" + title + "',NULL);";
            }
            else
            {
                int id = GetIdByTitle(parentTitle);
                str = "INSERT INTO dbo.category (title, parent_id) VALUES('" + title + "'," + id + ");";
            }
            SqlConnection connection = Library.Connection.Instance();
            SqlCommand command = new SqlCommand(str, connection);
            command.ExecuteNonQuery();

            MessageBox.Show("添加成功", "添加分类");
            tvCategory.Nodes.Clear();
            InitializeTreeViewCategory();
        }