How mysql updates one table to another

Solution 1: Modify 1 column

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

Solution 2: Modify multiple columns

update a, b

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

Solution 3: Using subqueries

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