mysql C 根据子查询的结果更新表中的多行

发布时间：2023-12-14 15:35:17 所属栏目：MySql 来源：DaWei

导读： 我有以下查询：

SELECT
stat.mcq_id,ROUND( stat.total_score / stat.num_taken,2 ) AS avg_score
FROM (
SELECT
user_mcq.mcq_id,SUM( score ) AS total_score,COU

我有以下查询：

SELECT stat.mcq_id,ROUND( stat.total_score / stat.num_taken,2 ) AS avg_score FROM ( SELECT user_mcq.mcq_id,SUM( score ) AS total_score,COUNT( user_mcq.id ) AS num_taken FROM user_mcq INNER JOIN user ON ( user.id = user_mcq.user_id ) WHERE user.level_id =3 AND user_mcq.is_complete =1 GROUP BY user_mcq.mcq_id ) AS stat

这会产生：

mcq_id avg_score 1 5.75 2 9.22 6 8.81 7 8.94 14 7.00 16 9.46

我想使用它来更新另一个名为mcq的表,使用结果中的mcq_id来匹配mcq.id

我尝试了以下,但没有成功：

UPDATE mcq SET mcq.avg_score = stats.avg_score FROM ( SELECT stat.mcq_id,COUNT( user_mcq.id ) AS num_taken FROM user_mcq INNER JOIN user ON ( user.id = user_mcq.user_id ) WHERE user.level_id =3 AND user_mcq.is_complete =1 GROUP BY user_mcq.mcq_id ) AS stat ) AS stats WHERE mcq.id = stats.mcq_id;

这给出了：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM ( SELECT stat.mcq_id,2 ) A' at line 1 最佳答案我认为您可以使用与表的连接并更新列,如下所示：

UPDATE mcq,(SELECT stat.mcq_id,2 ) AS avg_score FROM (SELECT user_mcq.mcq_id,SUM(score ) AS total_score,COUNT( user_mcq.id ) AS num_taken FROM user_mcq INNER JOIN user ON ( user.id = user_mcq.user_id ) WHERE user.level_id =3 AND user_mcq.is_complete =1 GROUP BY user_mcq.mcq_id ) AS stat ) AS stats SET mcq.avg_score = stats.avg_score WHERE mcq.mcq_id = stats.mcq_id;

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