已解决SQL_ERROR_INFO: “You have an error in your SQL syntax； check the manual that corresponds to your

已解决SQL_ERROR_INFO: “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 ‘.difficult_level\n (count(q1.question_id)/count(distinct q1.device_id)) as avg’ at line 3”

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报错代码

我的代码：

select 
    u.university
    q2.difficult_level
    (count(q1.question_id)/count(distinct q1.device_id)) as avg_answer_cnt
    
from  
    user_profile  as u 
    join question_practice_detail as q1 on u.device_id = q1.device_id
    join question_detail as q2 on q1.question_id = q2.question_id

where 
    university = '山东大学'
group by q2.difficult_level

报错信息：

SQL_ERROR_INFO: “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 ‘.difficult_level\n (count(q1.question_id)/count(distinct q1.device_id)) as avg’ at line 3”

报错原因

报错内容翻译：

SQL\u ERROR\u INFO：“您的SQL语法有错误；请查看与您的MySQL server版本对应的手册，以了解要在附近使用的正确语法。第3行的平均值为\u级（count（q1.question\u id）/count（distinct q1.device\u id））

报错原因：您的SQL语法有错误；请查看与您的MySQL server版本对应的手册

解决方法

SQL_ERROR_INFO: "You have an error in your SQL syntax; check the manual that corresponds to your...类似这种开头的错误，这种错误一般情况下就是多个标点符号啊，字段名字写错了等一系列因为手打失误出现的错误。

检查一下代码发现少了两个逗号：

修改代码后运行成功：

select 
    u.university,
    q2.difficult_level,
    (count(q1.question_id)/count(distinct q1.device_id)) as avg_answer_cnt
from  
    user_profile  as u 
    join question_practice_detail as q1 on u.device_id = q1.device_id
    join question_detail as q2 on q1.question_id = q2.question_id

where 
    university = '山东大学'
group by q2.difficult_level