Laravel 按日期分组

I am trying to make an elqouent query for a following sql,

select sum(w.total_item_count) as Day_count, w.created_at as created_at from `sales_flat_orders` as `w` group by DATE(`w`.`created_at`) order by `w`.`created_at` asc

我已经试过了

$orderbydate = DB::table('sales_flat_orders as w')
                ->select(array(DB::Raw('sum(w.total_item_count) as Day_count'),DB::Raw('DATE(w.created_at) as created_at')))
                ->groupBy('w.created_at')
                ->orderBy('w.created_at')
                ->get();

我在 sql 查询中得到了正确的输出，但在 eloquent 查询中却没有得到正确的输出，请帮忙，谢谢.

$orderbydate = DB::table('sales_flat_orders as w')
                ->select(array(DB::Raw('sum(w.total_item_count) as Day_count'),DB::Raw('DATE(w.created_at) day')))
                ->groupBy('day')
                ->orderBy('w.created_at')
                ->get();