mysql5.7的3065错误解决方案

有以下sql

SELECT DISTINCT questionid,questiontype 

FROM x2_questions AS questions,x2_quest2knows AS quest2knows 

WHERE  find_in_set(quest2knows.qkknowsid,:knowsid)  
AND quest2knows.qktype = 0  
AND quest2knows.qkquestionid = questions.questionid  
AND questions.questionstatus = 1  

ORDER BY questionparent asc,questionsequence 

运行时提示错误信息

Expression #1 of ORDER BY clause is not in SELECT list, references column 'pe6.questions.questionparent' which is not in SELECT list; this is incompatible with DISTINCT

错误原因：

mysql5.7版本中，如果DISTINCT和order by一起使用将会报3065错误，sql语句无法执行。这是由于5.7版本语法比之前版本语法要求更加严格导致的。

解决方案：

修改mysql的安全模式,即sql_mode。

步骤：
1.mysql终端中输入下面命令，查看相关配置信息

show variables like '%sql_mode%';
默认情况下可以看到如下信息
| sql_mode | 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

2.设置sql_mode去掉ONLY_FULL_GROUP_BY
推荐在mysql的配置文件my.cnf文件(linux)/my.ini文件(window) 的mysqld中增加或者修改sql_model配置选项

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

3.重启mysql生效
4.验证
在mysql终端中输入下面命令，查看结果。

show variables like '%sql_mode%';