题解 | 找出每个学校GPA最低的同学
找出每个学校GPA最低的同学
https://www.nowcoder.com/practice/90778f5ab7d64d35a40dc1095ff79065
#思路一：利用表的左连接，首先建立临时表：找到每个学校的最低gpa；再将临时表作为主表，与user_profile进行连接，条件控制学校和gpa，以找到其对应的device_id。
with a as (
select distinct
university,
min(gpa) as gpa
from user_profile
group by 1
)
select
b.device_id,
a.university,
a.gpa
from a
left join (
select * from user_profile
)b on b.gpa = a.gpa
and b.university = a.university
order by a.university
;
#思路二：利用窗口函数，over(partition by university order by gpa)
with a as (
select
device_id,
university,
gpa,
row_number()over(partition by university order by gpa) as rk
from user_profile
)
select
device_id,
university,
gpa
from a
where a.rk = 1
;
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