题解 | #分组过滤练习题#
分组过滤练习题
http://www.nowcoder.com/practice/ddbcedcd9600403296038ee44a172f2d
select university,
avg(question_cnt) as avg_question_cnt,
avg(answer_cnt) as avg_answer_cnt
from user_profile
group by university
having avg_question_cnt < 5 or avg_answer_cnt < 20;
where 和 group 不能一起使用，要注意如果要使用 where 同等效果，应该要用 having
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