update ord a
inner join room b on a.roomno=b.roomno
inner join flat c on a.flatno = c.flatno and a.flatsub=c.flatsub
set a.xrea = b.xrea,
a.ritysubn=b.ritysubn,
a.blockno=b.blockno,
a.blockn=b.blockn,
a.part=b.part,
a.unit=b.unit,
a.layer=b.layer,
a.home=b.home,
a.flatn=c.flatn;MySQL5.7多表关联更新
原文：http://blog.51cto.com/lavasoft/2114452
