这个需要嵌套吗,select * from student as a left join xbdm as b on a.xbdm=b.xbdm left join mzdm as c on a.mzdm=c.mzdm left join zzmmdm as d on a.zzmmdm=c.zzmmdm这个不行吗?
select id,xm,a.xbdm,a.mzdm,a.zzmmdm,xb,mz,zzmm from student a left join xbdm b on a.xbdm=b.xbdm left join mzdm c on a.mzdm=c.mzdm left join zzmmdm d on a.zzmmdm=d.zzmmdm你要的是这个结果吧?
on a.xbdm=b.xbdm left join mzdm as c
on a.mzdm=c.mzdm left join zzmmdm as d
on a.zzmmdm=c.zzmmdm这个不行吗?
student a
left join xbdm b on a.xbdm=b.xbdm
left join mzdm c on a.mzdm=c.mzdm
left join zzmmdm d on a.zzmmdm=d.zzmmdm你要的是这个结果吧?