摘要:
有三张表film category film_category left join 查询结果 select *from film f left join film_category fc on f.film_id=fc.f_id select *from film f left join film_ 阅读全文
摘要:
List<Person> list = new ArrayList<>(); 1.对象中的属性转map 通过Collectors.toMaplist.stream().collect(Collectors.toMap(Person::getId,Person::getName));2.收集对象本身l 阅读全文