Question

我正在尝试编写一个SQL查询，该查询将总结以下两个示例表中的总产量：

Table: CaseLots
DateProduced        kgProduced
October 1, 2013     10000
October 1, 2013     10000
October 2, 2013     10000

Table: Budget
OperatingDate       BudgetHours
October 1, 2013     24
October 2, 2013     24

我想输出一个表格如下：

TotalProduction   TotalBudgetHours    
30000                   48

到目前为止，我的代码是：

SELECT 
Sum(kgProduced) AS TotalProduction, Sum(BudgetHours) AS TotalBudgetHours
FROM 
dbo.CaseLots INNER JOIN dbo.Budget ON dbo.CaseLots.DateProduced = dbo.Budget.OperatingDate
WHERE 
dbo.Budget.OperatingDate BETWEEN '2013-10-01' AND '2013-10-02'

在一天中生成多个案例批次的情况下，查询似乎是对预算小时的双重总结。我得到的表格如下：

Total Production     BudgetHours
30000                72

我该如何解决这个问题？

Answer 1

想想INNER JOIN正在做什么。

对于CaseLot中的每一行，它会在Budget中查找具有匹配日期的任何行。

如果您要在SQL中删除聚合语句，只显示内部联接，您将看到以下结果集：

DateProduced kgProduced OperatingDate BudgetHours

2013年10月1日10000 10月1日，2013 24

2013年10月2日10000 10月2日，2013 24

（该死的StackOverflow，为什么你没有表格的Markdown :(）

在此基础上运行聚合，很容易看出你的结果是如何获得72小时的。

正确的查询需要首先聚合CaseLots表，然后加入Budget表。

SELECT DateProduced, TotalKgProduced, SUM(BudgetHours) AS TotalBudgetHours
FROM
(
    SELECT DateProduced, SUM(kgProduced) AS TotalKgProduced
    FROM CaseLots
    GROUP BY DateProduced
) AS TotalKgProducedByDay
INNER JOIN
Budget
ON TotalKgProducedByDay.DateProduced = Budget.OperatingDate
WHERE DateProduced BETWEEN '1 Oct 2013' AND '2 Oct 2013'
GROUP BY DateProduced

Answer 2

问题在INNER JOIN生成一个3行表，因为密钥匹配所有。所以有三个'24'，总和为72。

要解决此问题，将其拆分为两个查询可能会更容易。

SELECT Sum(kgProduced) AS TotalProduction
FROM dbo.CaseLots
WHERE dbo.CaseLots.OperatingDate BETWEEN '2013-10-01' AND '2013-10-02'

LEFT JOIN

SELECT Sum(BudgetHours) AS TotalBudgetHours
FROM dbo.Budget
WHERE dbo.Budget.OperatingDate BETWEEN '2013-10-01' AND '2013-10-02'

Answer 3

这可以通过以下方式轻松实现：

SELECT
   (SELECT SUM(kgProduced) FROM dbo.CaseLots WHERE DateProduced BETWEEN '2013-10-01' AND '2013-10-02') AS TotalProduction,
   (SELECT SUM(BudgetHours) FROM dbo.Budget WHERE OperatingDate BETWEEN '2013-10-01' AND '2013-10-02') AS TotalBudgetHours

没有必要加入这两个表格。

Answer 4

试试这个：

select DateProduced,TotalProduction,TotalBudgetHours from
  (select DateProduced,sum(kgProduced) as TotalProduction 
  from CaseLots group by DateProduced) p
  join
  (select OperatingDate,sum(BudgetHours) as TotalBudgetHours 
  from Budget group by OperatingDate) b
  on (p.DateProduced=b.OperatingDate)
where p.DateProduced between '2013-10-01' AND '2013-10-02'

Answer 5

对于这种特殊情况，其他答案更简单。但是，如果SUM表上需要CaseLots 10个不同的值，则需要10个不同的子查询。以下是一个通用的，更具可扩展性的解决方案：

SELECT 
    SUM(DayKgProduced) AS TotalProduction, 
    SUM(BudgetHours) AS TotalBudgetHours
FROM (
    SELECT 
        DateProduced,
        SUM(kgProduced) AS DayKgProduced, 
    FROM dbo.CaseLots 
    WHERE DateProduced BETWEEN '2013-10-01' AND '2013-10-02' 
    GROUP BY DateProduced
) DailyTotals
INNER JOIN dbo.Budget b ON DailyTotals.DateProduced = b.OperatingDate

首先，SUM生成每个CaseLot而不必SUM BudgetHours。如果您在上面的查询中使用SELECT * FROM，则会看到：

Date        DayKgProduced  BudgetHours
2013-10-01  20000          24 
2013-10-02  10000          24

但是你想要整体总数，所以我们SUM那些每日价值，正确地产生：

TotalProduction  TotalBudgetHours
30000            48

SQL Sum与非唯一日期

5 个答案: