private void btnDeleteUsers_Click(object sender, EventArgs e)
        {
            bool flag = false;

            if (selectedKeyIDList.Count == 0)
            {
                MessageBox.Show("请选择要删除的用户!");
            }
            else
            {
                foreach (string userID in selectedKeyIDList)
                {
                    UserBusinessLogic userBusinessLogic = new UserBusinessLogic();
                    flag = userBusinessLogic.DeleteUsersById(userID);
                }
                if (!flag)
                {
                    MessageBox.Show("删除失败!");
                }
                else
                {
                    MessageBox.Show("删除成功!");
                }
            }
            this.dgvUsers.DataSource = this.usersBindingSource;
            UserManageForm_Load(sender, e);
            selectedKeyIDList.Clear();
        }