Laravel 5.4 报错SQLSTATE[42000] Syntax error or access violation 1055 'xxx' isn't in GROUP BY

查询mysql 1055错误码发现问题为在mysql的配置中如果设置了sql_mode包含ONLY_FULL_GROUP_BY值得话，在进行查询时需要将select的字段都包含在group by 中。 即 select x,y from xxx group by x,y 否则就会报错

但是查看自己的配置my.cnf发现在sql_mode中并没有ONLY_FULL_GROUP_BY这个值

然后去查看Laravel的配置文件，config/database.php，查找mysql的配置，

'mysql' => [
            'driver' => 'mysql',
            'host' => env('DB_HOST', 'localhost'),
            'port' => env('DB_PORT', '3306'),
            'database' => env('DB_DATABASE', 'forge'),
            'username' => env('DB_USERNAME', 'forge'),
            'password' => env('DB_PASSWORD', ''),
            'charset' => 'utf8',
            'collation' => 'utf8_unicode_ci',
            'prefix' => env('DB_PREFIX',''),
            'strict' => true,
            'engine' => null,
        ],

发现有个strict项，默认为true，上网也没有查找到相关解释，根据字面意思猜测可能为是否开启严格模式，将其修改为false，再次测试发现问题解决，可以输出正确结果 源代码解释： vendor\laravel\framework\src\Illuminate\Database\Connectors\MySqlConnector.php 约144行

protected function setModes(PDO $connection, array $config)
    {
        if (isset($config['modes'])) {
            $this->setCustomModes($connection, $config);
        } elseif (isset($config['strict'])) {
            if ($config['strict']) {		//这边有个判断如果是true则执行strictMode()方法所以要改为false
                $connection->prepare($this->strictMode())->execute();
            } else {
                $connection->prepare("set session sql_mode='NO_ENGINE_SUBSTITUTION'")->execute();
            }
        }
    }
protected function strictMode()
    {
        return "set session 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'";
    }

也可以编辑 /etc/my.cnf 文件 在[mysqld]追加

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

重启mysql即可。