题解 | 找出每个学校GPA最低的同学
SELECT
device_id,
university,
gpa
FROM
(
SELECT
device_id,
university,
gpa,
-- 窗口函数，根据university分组，并按照gpa排序
ROW_NUMBER() OVER (
PARTITION BY
university
ORDER BY
gpa
) AS rn
FROM
user_profile
) t
WHERE
-- 只取每个分组的第一条
rn = 1;
