private void btnChangeUser_Click(object sender, EventArgs e) { if (ob_FrmUser != null && !ob_FrmUser.IsDisposed) { MessageBox.Show("请先关闭书城用户管理子系统再试!", "重试"); ob_FrmUser.Activate(); } else if (ob_FrmInfoAdmin != null && !ob_FrmInfoAdmin.IsDisposed) { MessageBox.Show("请先关闭个人信息管理子系统再试!", "重试"); ob_FrmInfoAdmin.Activate(); } else if (ob_FrmDataBase != null && !ob_FrmDataBase.IsDisposed) { MessageBox.Show("请先关闭备份与恢复数据库子系统再试!", "重试"); ob_FrmDataBase.Activate(); } else if (ob_FrmHelp != null && !ob_FrmHelp.IsDisposed) { MessageBox.Show("请先关闭系统使用帮助子系统再试!", "重试"); ob_FrmHelp.Activate(); } else if (ob_FrmBook != null && !ob_FrmBook.IsDisposed) { MessageBox.Show("请先关闭书籍信息管理子系统再试!", "重试"); ob_FrmBook.Activate(); } else if (ob_FrmStock != null && !ob_FrmStock.IsDisposed) { MessageBox.Show("请先关闭库存信息管理子系统再试!", "重试"); ob_FrmStock.Activate(); } else if (ob_FrmFinance != null && !ob_FrmFinance.IsDisposed) { MessageBox.Show("请先关闭财务信息子系统再试!", "重试"); ob_FrmFinance.Activate(); } else { FrmLogin ob_FrmLogin = new FrmLogin(); ob_FrmLogin.Show(); CDataBase.conn.Close(); this.Hide(); } }