SQL语句面试题

Question

问题描述

一张表，id class score，一条SQL语句，获得每个班级大于60分和小于60分的个数，结果为:
班级 大于60 小于60
A1 2 3
A2 1 2

补充

采纳了答案,我在想有没有更简单或者效率更高的sql语句

Answer 1

是这样吧。

SELECT
  class as 班级,
  (select count(score) from score c1 where score > 60 and c.class = c1.class) as 大于60,
  (select count(score) from score c2 where score < 60 and c.class = c2.class) as 小于60
FROM
    score c
GROUP BY
    class;

Answer 2

select class count(score as sc_under60) count(score as sc_above60)
from 表
where sc_under60 < 60 and sc_above60 > 60
group by class;

是这个意思么？

Answer 3

这样会好些吧！

SELECT class as 班级, COUNT(CASE when score>=60 THEN score END) as 大于60, COUNT(CASE when score<60 THEN score END) as 小于60 FROM test_class GROUP BY class