private void appointButton_Click(object sender, EventArgs e)//预约，预约时间必须后于当前时间（可能要涉及DateTime），并同时改动预约情况
{
BookShelfService.AppointBook(currentBook, currentClient);
this.appointButton.Enabled = false;
this.appointButton.Visible = false;
}
private void appointButton_Click(object sender, EventArgs e)//预约
{
BookShelfService.AppointBook(currentBook, currentClient);
this.appointButton.Enabled = false;
this.appointButton.Visible = false;
}