1. The cloud cause of the problem

After MySQL 5.7.5, ONLY_FULL_GROUP_BY is turned on by default, so some of the previous SQL cannot be executed normally. In fact, it is caused by our SQL irregularities, because after the group by, some data returned is uncertain, so it will This error occurred.

2. The error is as follows

{"code":1,"data":{},"msg":"\n### Error querying database.  Cause: java.sql.SQLSyntaxErrorException: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'a.id' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by\n### The error may exist in team/gk18software1dev/pcrsys/mapper/StudentMapper.java (best guess)\n### The error may involve team.gk18software1dev.pcrsys.mapper.StudentMapper.getListOnSelectByPcId-Inline\n### The error occurred while setting parameters\n### SQL: SELECT * from ( SELECT * from ( select student_choose_project.id,student_choose_project.stu_id, student_choose_project.pc_id,student_choose_project.p_id,student_choose_project.`status`, student.class_name,student.`name`,student.stu_number,student.telephone, student.station_name,student.wechat_num,student.email,student.remark from student_choose_project LEFT JOIN student on student_choose_project.stu_id=student.stu_id O

3. Solve

Turn off ONLY_FULL_GROUP_BY
Method 1:

• View

select @@global.sql_mode;

• Set up

set @@global.sql_mode ='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';

• Refresh

flush privileges;

Method Two:
Linux solution steps:

①, login into MySQL, linux login:mysql -u username -p , And then enter the password, enter SQL:show variables like '%sql_mode';

②. Edit the my.cnf file, the file address is generally:/etc/my.cnf，/etc/mysql/my.cnf,turn upsql-modePosition, removeONLY_FULL_GROUP_BY,thenRestart MySQL; Some my.cnf does not have sql-mode, you need to add:

sql-mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION，Note that if you want to add it under [mysqld], I just added it to other places, and it won't take effect after restarting.
　　
③, restart the MySQL service after the modification is successful,service mysql restartAfter restarting, log in to mysql and enter SQL:show variables like '%sql_mode'; If there is no ONLY_FULL_GROUP_BY, it meanssuccessUp.