sql_mode=only_full_group_by

出现场景

mysql 执行报错：Error querying database. Cause: java.sql.SQLSyntaxErrorException:which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

出现原因
1.这个错误发生在mysql 5.7 版本及以上版本会出现的问题：
mysql 5.7版本默认的sql配置是:sql_mode=“ONLY_FULL_GROUP_BY”，这个配置严格执行了"SQL92标准"
2.在sql执行时，出现该原因：
简单来说就是：输出的结果是叫target list，就是select后面跟着的字段，还有一个地方group by column，就是group by后面跟着的字段。由于开启了ONLY_FULL_GROUP_BY的设置，所以如果一个字段没有在target list
和group by字段中同时出现，或者是聚合函数的值的话，那么这条sql查询是被mysql认为非法的，会报错误。

解决方法

1. 临时解决方法

select @@global.sql_mode;
结果如下：
ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION 
去掉ONLY_FULL_GROUP_BY即可
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 

2. 永久解决方法
   修改配置文件，不同系统的配置文件路径不同：
3. Mac或Linux文件 /etc/mysql/my.cnf
4. windows 在数据库安装目录下的 my.ini
   在[mysqld]下加sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
   如下所示

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
skip-host-cache
skip-name-resolve
datadir=/var/lib/mysql
socket=/var/run/mysqld/mysqld.sock
secure-file-priv=/var/lib/mysql-files
user=mysql

sql_mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

#log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[client]
socket=/var/run/mysqld/mysqld.sock