题解 | #分组计算练习题#
分组计算练习题
http://www.nowcoder.com/practice/009d8067d2df47fea429afe2e7b9de45
select gender,university,count(device_id) user_num,
avg(active_days_within_30) avg_active_day,avg(question_cnt) avg_question_cnt
from user_profile
group by university,gender
- 对大学和性别分组，group by university,gender；
- 计数，count(device_id)；
- 求平均，avg(active_days_within_30) , avg(question_cnt)。
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