问在laravel中用addselect()连接同一个表的两个左连接

EN

$warehouse_transfer = WarehouseTransfer::mySelect(array('date', 'from_warehouse_id', 'to_warehouse_id'))
            ->where('warehouse_transfer.id', $id)
            ->first();

public function scopeMySelect($q, $columns = array()) {
    $q->addSelect("warehouse_transfer.id")
    // date
    if (in_array('date', $columns)) {
        $q->addSelect(DB::raw("DATE_FORMAT(oops_warehouse_transfer.date, '%d-%m-%Y') as date"));
    }

    // Warehouse Transfer From
    if (in_array('from_warehouse_id', $columns)) {
        $q->addSelect("warehouse_transfer.from_warehouse_id");
        $q->addSelect('warehouse_transfer.from_warehouse_id', 'w1.name AS from_warehouse_name');
        ->leftJoin('warehouse As w1', 'w1.id', '=', 'warehouse_transfer.from_warehouse_id');
    }
    // Warehouse Transfer To
    if (in_array('to_warehouse_id', $columns)) {
        $q->addSelect("warehouse_transfer.to_warehouse_id");
        $q->addSelect('warehouse_transfer.to_warehouse_id', 'w2.name AS to_warehouse_name');
        ->leftJoin('warehouse AS w2', 'warehouse_transfer.to_warehouse_id', '=', 'w2.id');
     }
     // Warehouse Transfer Staff Name
     if (in_array('staff_name', $columns)) {
         $q->addSelect("staff.name as staff_name")
                ->leftjoin('staff', 'staff.id', '=', 'warehouse_transfer.staff_id');
      }

      // Warehouse Transfer ITP
      if (in_array('itp', $columns)) {
          $q->addSelect("warehouse_transfer.itp");
      }

      // Warehouse Transfer UTP
      if (in_array('utp', $columns)) {
          $q->addSelect("warehouse_transfer.utp");
      }
}

1   id
2   name
3   code
4   status
5   itp
6   utp 

1   id
2   date
3   from_warehouse_id
4   to_warehouse_id
5   staff_id
6   itp
7   utp