Question

我需要对数据库中的各个表执行多项计数我希望将这些计数合并为一个结果。

协调以下查询：

SELECT 100 As SomeCount
SELECT 200 As SomeOtherCount
SELECT 300 As YetAnotherCount

如果我使用UNION组合它们，则每个结果将在最终结果中排成一行：

SELECT 100 As SomeCount
UNION
SELECT 200 As SomeOtherCount
UNION
SELECT 300 As YetAnotherCount

输出：

> SomeCount
> --------- 
> 100 
> 200 
> 300

我想要的是

> SomeCount | SomeOtherCount | YetAnotherCount
> --------------------------------------------
>   100     |      200       |     300

我能想到“命名”结果的另一种方法就是使用类似的东西：

SELECT 'SomeCount' As Name, 100 As Value
UNION ALL
SELECT 'SomeOtherCount', 200
UNION ALL
SELECT 'YetAnotherCount', 300

在这种情况下结果如下：

>     Name          |      Value
> ---------------------------------
> 'SomeCount'       |       100
> 'SomeOtherCount'  |       200
> 'YetAnotherCount' |       300

有没有办法得到我想要的结果，或者是最后一种方法？

我应该提一下上面的查询非常简单，以便解释核心问题。实际上，需要组合的两个查询可能如下所示：

查询1：

SELECT Count(Id) As UndeliveredSms
FROM
(
 SELECT Id
 FROM IncomingSms
 WHERE Id NOT IN (SELECT IncomingSmsId
                  FROM DeliveryAttempt
                  WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
 )

查询2：

SELECT Count(Id) As UndeliveredEMail FROM
(
 SELECT Id
 FROM IncomingEMail
 WHERE Id NOT IN (SELECT IncomingEMailId
                  FROM DeliveryAttempt
                  WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
)

将这些内容包含在另一个SELECT语句中不适用于SQlite。

使用示例中的最后一个方法确实有效，我可能会去使用该解决方案，除非这是一个坏主意：

SELECT 'UndeliveredSms' As Name,  Count(Id) As Value
FROM
(
 SELECT Id
 FROM IncomingSms
 WHERE Id NOT IN (SELECT IncomingSmsId
                  FROM DeliveryAttempt
                  WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
 )

UNION

SELECT 'UndeliveredEMail', Count(Id) FROM
(
 SELECT Id
 FROM IncomingEMail
 WHERE Id NOT IN (SELECT IncomingEMailId
                  FROM DeliveryAttempt
                  WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
)

结果是这样的：

>     Name           |     Value
> ---------------------------------
> UndeliveredEMail   |       82
> UndeliveredSms     |       0

当然，实际上，还有很多事情可以计算

Answer 1

您应该能够在查询之间使用CROSS JOIN：

SELECT *
FROM
(
  SELECT Count(Id) As UndeliveredSms
  FROM
  (
   SELECT Id
   FROM IncomingSms
   WHERE Id NOT IN (SELECT IncomingSmsId
                    FROM DeliveryAttempt
                    WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
  )
)
CROSS JOIN
(
  SELECT Count(Id) As UndeliveredEMail FROM
  (
   SELECT Id
   FROM IncomingEMail
   WHERE Id NOT IN (SELECT IncomingEMailId
                    FROM DeliveryAttempt
                    WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
  )
);

请参阅SQL Fiddle with Demo

Answer 2

我不理解你的查询中使用UNION，但也许我误会了。不是在一个子集联合中，而不是在一个子集中......

似乎可以简化为以下内容：

select *
from
(
  SELECT Count(Id) As UndeliveredSms
  FROM IncomingSms
  WHERE Id NOT IN (SELECT IncomingSmsId
                    FROM DeliveryAttempt
                    WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
) t, 
(
  SELECT Count(Id) As UndeliveredEMail 
  FROM IncomingEMail
  WHERE Id NOT IN (SELECT IncomingEMailId
                    FROM DeliveryAttempt
                    WHERE Status = 'Delivered' OR Status = 'FailedPermanently')
  ) t2

将多个结果组合为列，而不是行

2 个答案: