public object Login(string identityCard, string passWord) { Teacher teacher = new Teacher(); Student student = new Student(); StudentDAL studentDAL = new StudentDAL(); TeacherDAL teacherDAL = new TeacherDAL(); try { student = studentDAL.SelectByProperty(s => s.IdentityCard.Trim() == identityCard.Trim()).FirstOrDefault(); teacher = teacherDAL.SelectByProperty(t => t.IdentityCard.Trim() == identityCard.Trim()).FirstOrDefault(); if (student !=null) { if (student.PassWord.Trim() == passWord.Trim()) return student; else throw new ViladationException(new RuleViolation("�����ȷ.")); } else if (teacher!=null) { if (teacher.PassWord.Trim() == passWord.Trim()) return teacher; else throw new ViladationException(new RuleViolation("�����ȷ.")); } else throw new ViladationException(new RuleViolation("�������!")); } catch (AccessDataException ac) { throw ac; } }