mysql用一个表更新另一个表

Solution 1:  1列

update student s, city c
   set s.city_name = c.name
 where s.city_code = c.code;

Solution 2:  多个列

update  a,  b

set a.title=b.title, a.name=b.name
where a.id=b.id

Solution 3: 子查询

update student s set city_name = (select name from city where
code = s.city_code);