简化查询以获取行总和

Question

我使用以下SQL从数据库中获取物流成本：

SELECT country, sum(Costs_Inbound), sum(Costs_Storage), sum(Costs_Outbound),
       (sum(Costs_Inbound) + sum(Costs_Storage) + sum(Costs_Outbound)) as Total
FROM Logistics
GROUP BY country WITH ROLLUP;

可以找到here，其中包含数据库的SQL Fiddle。
到目前为止，所有这些工作正常。

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现在，我想知道是否可以通过引用第一行中的列表达式来简化第二个sum语句，因为-如您所见-现在，我将第一行中的每个列表达式复制到第二行中。 / p>

Answer 1

您可以使用单个SUM()对其进行简化：

SELECT country, SUM(Costs_Inbound), SUM(Costs_Storage), SUM(Costs_Outbound),
       SUM(Costs_Inbound + Costs_Storage + Costs_Outbound) as Total
FROM Logistics
GROUP BY country WITH ROLLUP;