请问我这个SQL哪错了哪错了

update mbb set mbb.bs=newhljmzb.mzmc from newhljmzb where mbb.ksh=newhljmzb.ksh
请问 我这句SQL语句哪错了？
[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'from newhljmzb where mbb.ksh=newhljmzb.ksh' at line 1

 update mbb set mbb.bs=(select  mzmc from newhljmzb where mbb.ksh=newhljmzb.ksh)

update mbb set mbb.bs= 这个后面必须是查询语句，而且是唯一的结果

update A , B set A.编码=B.编码 where A.编码=B.编码

update A , B set A.编码=B.编码 where A.编码=B.编码

子语句缺少select