update student s, city c
set s.city_name = c.name
where s.city_code = c.code;这个写法会造成city锁死,有哪些方案可以避免,降低MySQL的数据隔离级别是最好吗?
set s.city_name = c.name
where s.city_code = c.code;这个写法会造成city锁死,有哪些方案可以避免,降低MySQL的数据隔离级别是最好吗?
begin
FOR i IN 0..99 LOOP
update student s, city c
set s.city_name = c.name
where s.city_code = c.code and mod(s.city_code,100);
END LOOP;
end ;