SELECT u.university as university, COUNT( q.question_id )/COUNT(DISTINCT q.device_id ) as avg_answer_cnt FROM user_profile u LEFT JOIN question_practice_detail q ON u.device_id = q.device_id GROUP BY u.university order by u.university; 这个查询结果一模一样,不知道为啥不让我过
2
牛客网
牛客网在线编程
牛客网题解
牛客企业服务