public bool ChangePassword(int staffId, string oldPassword, string newPassword)
        {
            var entity = dal.GetStaffByStaffId(staffId);

            if (entity == null)
            {
                return(false);
            }
            if (!entity.Password.Equals(oldPassword))
            {
                return(false);
            }

            return(dal.ChangePassword(entity, newPassword));
        }