Laravel Query Builder在groupBy之后停止工作

Question

$records = DB::table('history as a')
    ->join('reservation2 as b', function($join){
      $join->on('a.id', '=', 'b.id')
      ->on('a.sid', '=', 'b.sid');
    })
    ->whereBetween('a.date', [$sDate, $eDate])
    ->select('a.*', DB::raw('SUM(a.perday) AS revenue'), 'b.name', 'b.checkin', 'b.checkout', 'b.status')
    ->groupBy('a.id')
    ->groupBy('a.sid')
    ->toSql();

给我以下查询：

select `a`.*, SUM(a.perday) AS revenue, `b`.`name`, `b`.`checkin`, `b`.`checkout`,
       `b`.`status` 
from `history` as `a` 
inner join `reservation2` as `b` on `a`.`id` = `b`.`id` and `a`.`sid` = `b`.`sid` 
where `a`.`date` between ? and ? group by `a`.`id`, `a`.`sid`

如果从mysql命令提示符传递查询，则显示许多记录但如果我用->toSql()替换->get()，则它不会给我任何记录。

有什么问题？