MySQL 查询case

select t.dealer_id_fk,person.NAME,att.update_date,a.name,a.path
from  
tr_dealer_manage_person t
LEFT JOIN t_manage_person person on t.manage_person_id_fk=person.id
LEFT JOIN (
	select manage_person_id_fk,max(update_date) update_date from t_attachment t  
	GROUP BY manage_person_id_fk
) att 
on att.manage_person_id_fk=t.manage_person_id_fk
LEFT JOIN t_attachment a on att.manage_person_id_fk=a.manage_person_id_fk and att.update_date=a.update_date
where t.dealer_id_fk ='1ad7d6ac-601c-11e4-800f-40f2e9db2692' and t.end_date IS NULL;