HQL聚合查询

HQL聚合查询

其实是考察的聚合函数

1.count函数（统计数量）

select count(name) from film where dates like'2014%';

2.平均

select avg(prince) from film where dates like'2015%';

平均以后保留两位小数

select round(avg(prince),2) from film where dates like'2015%';

3.最值问题

select max(prince) from film where dates like'2016%';

select min(prince) from film where dates like'2014%' or dates like'2016%';

4.排序分组

票房前5的电影

select name,sum(prince) p from film group by name order by p desc limit 5；降序排列

4.分组以后组内条件用having表示

select name,sum(prince) p from film group by name having p>700;

总结：降序为desc，升序asc