题解 | #分组过滤练习题#

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)

HAVING 子句

在 SQL 中增加 HAVING 子句原因是，WHERE 关键字无法与聚合函数一起使用。

HAVING 子句可以让我们筛选分组后的各组数据。