SQL 查询报错：Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'xxx' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
场景大概如下：
有成绩表score, 字段有math,age.....等等，我现在要查询各个年龄学生数学成绩的总和并降序排序.
select sum(math) mathScore,
age
from score
group by age
order by math;
然后查询报错上述错误，由于当时脑子有点短路，实在没发现错哪里，就上网查了查，基本都是说怎么怎么改配置，甚至有的离谱到说group by中出现的字段order by中也要有！
于是我放弃了，该配置是不可能的，报错就改配置，那开发团队还怎么玩！所以一个重新看看报错信息，大概意思是order by 中的条件功能上依赖group by中的内容，而在order by 中没有group by后的结果和条件。然后在看查询，也算明白原因了。修改查询:
select sum(math) mathScore,
age
from score
group by age
order by mathScore;
报错问题解决，原因group by的结果是math的聚和，而order by却是用最初的字段排序。
低级低级！脑壳昏！
