5.7版本mysql查询报错：com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException:...this is incompatible with sql_mode=only_full_group_by

　　先瞧下日志：

### Error querying database.  Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'test.wlf_appinfo.appname' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
### The error may involve WLFAppinfoMapper.getAppIdAndName-Inline
### The error occurred while setting parameters
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'test.wlf_appinfo.appname' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'test.wlf_appinfo.appname' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by] with root cause
 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'test.wlf_appinfo.appname' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.Util.getInstance(Util.java:387)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:939)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3878)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3814)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2478)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2625)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2551)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1861)
    at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1192)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:2931)
    at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_execute(FilterEventAdapter.java:440)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:2929)
    at com.alibaba.druid.proxy.jdbc.PreparedStatementProxyImpl.execute(PreparedStatementProxyImpl.java:118)
    at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:493)
    at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:45)
    at com.sun.proxy.$Proxy40.execute(Unknown Source)
    at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:39)
    at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:55)
    at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:41)
    at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:238)
    at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:112)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:78)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:72)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:338)
    at com.sun.proxy.$Proxy14.selectList(Unknown Source)
    at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:189)
    at com.iflytek.vbox.system.dao.BaseDao.getList(BaseDao.java:50)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1374)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

　　日志里已经告诉我们说Group By语法有问题了，那么问题何在？还得先看mysql的sql方式：

mysql> select @@sql_mode;
+-------------------------------------------------------------------------------------------------------------------------------------------+
| @@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 |
+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

　　我们看第一个ONLY_FULL_GROUP_BY： 对于GROUP BY聚合操作，如果在SELECT中的列，没有在GROUP BY中出现，那么这个SQL是不合法的，因为列不在GROUP BY从句中。

　　接着看下我们的查询语句：

select DISTINCT(appid),appname from wlf_appinfo GROUP BY appid order by appid desc;

　　在select里有appname，但group by却没有，因此不满足ONLY_FULL_GROUP_BY的要求。

　　如何解决？要么改sql_mode，去掉ONLY_FULL_GROUP_BY，要么改查询语句，在GROUP BY后面加上appname。第一种改法可以直接修改mysql配置文件mysqld.cnf，如果里面有sql_mode这一项，就去掉ONLY_FULL_GROUP_BY，没有就把上面查到的sql_mode配上，但不要加上ONLY_FULL_GROUP_BY即可，如：

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

　　如若只想当前会话生效，简单：

mysql> set sql_mode="STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected (0.01 sec)

mysql> select @@sql_mode;
+------------------------------------------------------------------------------------------------------------------------+
| @@sql_mode                                                                                                             |
+------------------------------------------------------------------------------------------------------------------------+
| STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)