我想在下面的query.below query中为工作sql编写laravel查询。如何在laravel for postgresql db中正确执行上面的查询

select  id,
        user_name,
        reported_to 
from    (select * from user_master
         order by reported_to) orrdered,
        (select @pv := 'prathap Achuthan') initialisation
where   find_in_set(reported_to, @pv)
and     length(@pv := concat(@pv, ',', user_name))