Add raw SQL to database query builder

I have the following SQL which provides me with the position of a particular record in the database given specific filters and ordering.

\DB::select("SELECT
    t.id,
    t.position
  FROM (
    SELECT estimations.id,
    @rownum := @rownum + 1 AS position
    FROM estimations
    JOIN (SELECT @rownum := 0) r
    WHERE estimations.is_archived = 1
    ORDER BY estimations.start desc, estimations.name) t
  WHERE t.id = " . $this->id);

For the inner query, I want to use the eloquent model Estimation so that I can use its query scopes. I want to use the model so that if the scope is updated down the line, this query will reflect the change...

$innerQuery = Estimation::select('id')
    ->addSelect(\DB::raw('@rownum := @rownum + 1 AS position'))
    // Need to add "JOIN (SELECT @rownum := 0) r" 
    ->archived();

Attempt 1 - failed

Use the join method and pass in some generic arguments...

$innerQuery = Estimation::select('id')
   ->addSelect(\DB::raw('@rownum := @rownum + 1 AS position'))
   ->join('(SELECT @rownum := 0) r', '1', '=', '1')
   ->archived();

While the above gives me the correct SQL if I dump it, $innerQuery->toSql() it fails when I run it, $innerQuery->get() with the following error...

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'my_db.(select @rownum := 0) r' doesn't exist (SQL: SELECT temp.id, temp.position FROM (select `id`, @rownum := @rownum + 1 AS position from `estimations` inner join `(SELECT @rownum := 0) r` on `1` = `1` where `is_archived` = ? order by `start` desc, `name` asc) temp WHERE temp.id = 4)

Attempt 2 - failed

As above but using DB::raw() for the join() (suggested by Jonas Staudenmeir),

$innerQuery = Estimation::select('id')
   ->addSelect(\DB::raw('@rownum := @rownum + 1 AS position'))
   ->join(\DB::raw('(SELECT @rownum := 0) r'), '1', '=', '1')
   ->archived();

Running $innerQuery->get() results in the following error...

SQLSTATE[42S22]: Column not found: 1054 Unknown column '1' in 'on clause' (SQL: select `id`, @rownum := @rownum + 1 AS position from `estimations` inner join (SELECT @rownum := 0) r on `1` = `1` where `is_archived` = 1 order by `start` desc, `name` asc)

Attempt 3 - failed

As above, adding DB::raw() for all join() values (thanks again Jonas Staudenmeir),

$innerQuery = Estimation::select('id')
   ->addSelect(\DB::raw('@rownum := @rownum + 1 AS position'))
   ->join(\DB::raw('(SELECT @rownum := 0) r'), \DB::raw('1'), '=', \DB::raw('1'))
   ->archived();

This works on its own $innerQuery->get();, but when inserted into the outer query,

$res = \DB::select('SELECT
    t.id,
    t.position
  FROM (' . $innerQuery->toSql() . ') t
  WHERE t.id = ' . $this->id);

I get the error...

SQLSTATE[HY000]: General error: 2031 (SQL: SELECT t.id, t.position FROM (select `id`, @rownum := @rownum + 1 AS position from `estimations` inner join (SELECT @rownum := 0) r on 1 = 1 where `is_archived` = ? order by `start` desc, `name` asc) t WHERE t.id = 3)

Is this because scopeArchived() filters by a value, which is shown as a ? in the error? How can I avoid this?

Here's the code for scopeArchived(),

public function scopeArchived($query)
{
    return $query->where('is_archived', true)->ordered('start', 'desc');
}

Removing ->where('is_archived', true) results in no error, but obviously not the results I'm after.

Attempt 4 - solved

(Thanks Jonas Staudenmeir) - use fromSub() for the outer query. Here's the complete code...

$innerQuery = Estimation::select('id')
    ->addSelect(\DB::raw('@rownum := @rownum + 1 AS position'))
    ->join(\DB::raw('(SELECT @rownum := 0) r'), \DB::raw('1'), '=', \DB::raw('1'))
   ->archived();

$res = \DB::query()->fromSub($innerQuery, 'temp')
    ->select('id', 'position')
    ->where('id', $this->id)
    ->first();