select need.*,(case user_class_id when '3' then (select real_name from bussiness_person_info where need.username=bussiness_person_info.username) else (select simple_name from bussiness_enterprise_info where need.username=bussiness_enterprise_info.username) end ) as author_name from bussiness_needs as need ;
通過user_class_id的分類，搜索不一樣的表，因爲比如發需求，這個用戶可能是企業商家，也可能是個人商家。他們的表不一樣的，要獲取的內容，只有通過user_class_id的區分來獲取！
如果通過系統用戶還要獲取微信的頭像和暱稱，就更復雜些，如下：
select need.*,weixin_user.nickname,weixin_user.headimgurl,(case user_class_id when '3' then (select real_name from bussiness_person_info where need.username=bussiness_person_info.username) else (select simple_name from bussiness_enterprise_info where need.username=bussiness_enterprise_info.username) end ) as author_name from bussiness_needs as need left join ucenter_member on need.username=ucenter_member.username left join weixin_union_member as un on ucenter_member.id=un.member_id left join weixin_user on un.uid=weixin_user.id;