DB门面/模型 -> join 联列方式的名称(关联的表名, 表1的字段, 运行符, 表2的字段)

左外联接

左外联接的原生SQL语句

SELECT
    a1.*,
    a2.auth_name as parent_name
FROM
    auth AS a1
    LEFT JOIN auth AS a2 ON a1.pid = a2.id

对应的代码写法

$data = DB::table('auth as a1') 
                                -> select('a1.*', 'a2.auth_name as parent_name')
                -> leftJoin('auth as a2', 'a1.pid', '=', 'a2.id') -> get();
dd($data);