题解 | 分组过滤练习题
分组过滤练习题
https://www.nowcoder.com/practice/ddbcedcd9600403296038ee44a172f2d
#思路: 先将表中数据按照大学名字进行分组并计算每组的聚合函数,然后对group by分组后的结果用having进行过滤约束
#注意: group by的结果用having,而不是where
select
university,
ROUND(AVG(question_cnt),3) avg_question_cnt,
ROUND(AVG(answer_cnt),3) avg_answer_cnt
from user_profile
GROUP BY university
having avg_question_cnt < 5.000 or avg_answer_cnt < 20.000;
