laravel查询读取主库

方法1（推荐）： 

DB::connection('write')->table('a')->get();

#在 config/database.php 配置文件里面配置读库
'write' => [
            'driver'    => 'mysql',
            'host'      => env('DB_WRITE_HOST', 'localhost'),
            'database'  => env('DB_DATABASE', 'forge'),
            'username'  => env('DB_USERNAME', 'forge'),
            'password'  => env('DB_PASSWORD', ''),
            'charset'   => 'utf8',
            'collation' => 'utf8_unicode_ci',
            'prefix'    => '',
            'strict'    => false,
        ],
#手动链接主库查询
DB::connection('write')->table('a')->get();

方法2： 

 DB::table('a')->lock()->get();

方法3：

$sql = 'select * from a';
DB::select($sql, [], false);

方法4： 仅供参考

$pdo = DB::connection()->getPdo();
$data=DB::connection()->setPdo($pdo)->table('a')->get();

方法5（推荐）：

$sql = 'select * from a';
DB::selectFromWriteConnection($sql);