Mysql left join 博客分类： DB-Mysql Mysql左连接

Mysql left join:

 case 1:

select ifnull(tv2.venueName,tv1.venueName) as venueName,ts.ticketSubtypeName, a.* 
from t_ticket a left join t_ticket_subtype ts on a.ticketSubtypeId=ts.id left join t_venue tv2 on ts.venueId=tv2.id left join t_venue tv1 on a.venueId=tv1.id 
where  a.id=1;

 

case 2:

select tv.venueName,ta1.name createUser,ta2.name updateUser, FROM_UNIXTIME(t.createTime/1000) createTimeStr,t.* 
from 
t_ticket_subtype t left join admin_user ta1 on t.createUser=ta1.id 
left join admin_user ta2 on t.updateUser=ta2.id 
left join t_venue tv on t.venueId=tv.id
where t.id=1
order by id desc;