sql 多表修改多字段

update T  set  T.Username='ceshi1' FROM (SELECT tu.uid, tu.company,tu.province,tu.create_time,tub.Username,tub.Mobile,tr.name ,tu.valid_time FROM 
   tu  left join  tub on  tu.authid=tub.UserId 
   left join  tr on tu.roid=tr.roid   WHERE  tu.uid=46
   )as T //括号里面写多表关联查询  需要修改的字段直接通过别名T点出来就okl