【問題解決】Expression #30 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'zxj
問題描述：
安裝了mysql5.7，用group by 查詢時丟擲如下異常：
Expression #30 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'zjrxmis.b.spec' which is not functionally dependent on columns in GROUP BY clause問題解決：
執行以下兩個命令：
mysql> 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';
AND
mysql> set session sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';這兩個命令，去掉 sql_mode 的 ONLY_FULL_GROUP_BY
原因分析：
MySQL 5.7.5和up實現了對功能依賴的檢測。如果啟用了only_full_group_by SQL模式(在預設情況下是這樣)，那麼MySQL就會拒絕選擇列表、條件或順序列表引用的查詢，這些查詢將引用組中未命名的非聚合列，而不是在功能上依賴於它們。(在5.7.5之前，MySQL沒有檢測到功能依賴項，only_full_group_by在預設情況下是不啟用的。關於前5.7.5行為的描述，請參閱
執行以下個命令，可以檢視 sql_mode 的內容。
mysql> SHOW SESSION VARIABLES;
mysql> SHOW GLOBAL VARIABLES;
mysql> select @@sql_mode;可見session和global 的sql_mode的值都為： 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
only_full_group_by說明： only_full_group_by ：使用這個就是使用和oracle一樣的group 規則, select的列都要在group中,或者本身是聚合列(SUM,AVG,MAX,MIN) 才行，其實這個配置目前個人感覺和distinct差不多的，所以去掉就好 官網摘抄： 官網：ONLY_FULL_GROUP_BY Reject queries for which the select list, HAVING condition, or ORDER BY list refer to nonaggregated columns that are neither named in the GROUP BY clause nor are functionally dependent on (uniquely determined by) GROUP BY columns.
As of MySQL 5.7.5, the default SQL mode includes ONLY_FULL_GROUP_BY. (Before 5.7.5, MySQL does not detect functional dependency and ONLY_FULL_GROUP_BY is not enabled by default. For a description of pre-5.7.5 behavior, see the MySQL 5.6 Reference Manual.)
A MySQL extension to standard SQL permits references in the HAVING clause to aliased expressions in the select list. Before MySQL 5.7.5, enabling ONLY_FULL_GROUP_BY disables this extension, thus requiring the HAVING clause to be written using unaliased expressions. As of MySQL 5.7.5, this restriction is lifted so that the HAVING clause can refer to aliases regardless of whether ONLY_FULL_GROUP_BY is enabled.