题解 | #分组过滤练习题#
分组过滤练习题
https://www.nowcoder.com/practice/ddbcedcd9600403296038ee44a172f2d
select university,
round(avg(question_cnt),3) as avg_question_cnt,
round(avg(answer_cnt),3) as avg_answer_cnt
from user_profile
group by university
having avg(question_cnt)<5 or avg(answer_cnt)<20
where子句在聚合前先筛选记录，也就是说作用在group by 子句和having子句前，而 having子句在聚合后对组记录进行筛选
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