Laravel 5.4 查询生成器来自两个不同表的 SUM()

Question

我在从两个表中获取某个字段的总和时遇到问题。

首先，这是我的查询。

        //Getting of Cost of Goods Sold (Menus)
        $totalMenuCost = DB::raw('(SUM(orders.qty * orders.cost)) as cost');
        $yearMenuSold = DB::raw('YEAR(orders.created_at) as year');

        $menuscost =  DB::table('orders')
            ->where('status', 'served')
            ->select($totalMenuCost, $yearMenuSold);

        //Getting of Cost of Goods Sold (Items)
        $totalItemCost = DB::raw('(SUM(purchases.qty * purchases.cost)) as cost');
        $yearItemSold = DB::raw('YEAR(purchases.created_at) as year');

        $itemcost =  DB::table('purchases')
            ->where('status', 'served')
            ->union($menuscost)
            ->select($totalItemCost, $yearItemSold)
            ->get();

当我尝试这样做时return $itemcost。它返回两行：

[
  {
    cost: "792.00",
    year: 2017
  },

  {
    cost: "1700.00",
    year: 2017
  }
]

我试图让它返回一行但添加它，如下所示：

[
  {
    cost: "2492.00", // that's 1,700 + 792
    year: 2017
  }
]

Answer 1

$itemcost =  DB::table('purchases')
            ->where('status', 'served')
            ->union($menuscost)
            ->select($totalItemCost, $yearItemSold)
            ->get();

在您的示例中，您只需从其他表 ($menuscost) 中选择 $totalItemCost、$yearItemSold 和并集。

所以这不会将结果相加。

///////////尝试以这种格式更改您的查询

select column1,sum(column2) total
from
(
    select column1,column2
    from Table1
    union all
    select column1,column2
    from Table2
) t
group by column1

希望这有帮助..如果需要更多帮助，请告诉我。