如何获得多个 SUM 语句的总数

Question

我有两列需要根据 WHERE 语句求和，然后每列 returns 总和，我还需要将得到的 SUM 值相加得到最终总和。

我可以使用 UNION ALL 获取每列的单独 SUM 值，但无法将它们相加得出最终总数。

SELECT ISNULL(SUM(NILH1), 0) AS SUM
FROM [IG_300M19].[dbo].[Stn14_RFT]
WHERE NILH1 <= 25
  AND DateStamp BETWEEN '2019-03-17 08:00' AND '2019-04-17 08:00'

UNION ALL

SELECT ISNULL(SUM(NILH2), 0) AS SUM
FROM [IG_300M19].[dbo].[Stn14_RFT]
WHERE NILH2 <= 25
  AND DateStamp BETWEEN '2019-03-17 08:00' AND '2019-04-17 08:00';

以上returns两个值，一个是NILH1，一个是NILH2，现在我需要把它们加在一起得到最终的总数。

Answer 1

考虑到两个查询具有相同的 WHERE 这不是那么简单：

SELECT SUM(ISNULL(CASE WHEN NILH1 <= 25 THEN NILH1 END, 0)) AS NILH1SUM,
       SUM(ISNULL(CASE WHEN NILH2 <= 25 THEN NILH2 END, 0)) AS NILH2SUM,
       SUM(ISNULL(CASE WHEN NILH1 <= 25 THEN NILH1 END, 0) + ISNULL(CASE WHEN NILH2 <= 25 THEN NILH2 END, 0)) AS TotalSum
FROM [IG_300M19].[dbo].[Stn14_RFT]
WHERE DateStamp BETWEEN '2019-03-17 08:00' AND '2019-04-17 08:00';

要在一个列上执行 SUM，您不需要多个 SELECT 语句，您可以在同一语句中对多个列进行聚合，并可以使用这些表达式进一步计算。

Answer 2

使用条件聚合；将条件从 WHERE 子句移动到 SUM 函数：

SELECT SUM(
    CASE WHEN NILH1 <= 25 THEN NILH1 ELSE 0 END +
    CASE WHEN NILH2 <= 25 THEN NILH2 ELSE 0 END
)
FROM [IG_300M19].[dbo].[Stn14_RFT]
WHERE DateStamp BETWEEN '2019-03-17 08:00' AND '2019-04-17 08:00'

Answer 3

对于这样的示例数据：

select * into #tab from (
    select 1 as NILH1,  2 as NILH2, cast('2019-03-17 18:00' as datetime) as DateStamp
    union all select 2, 3, cast('2019-03-17 18:00' as datetime)
    union all select 3, 4, cast('2019-03-17 18:00' as datetime)
    union all select 4, 5, cast('2019-06-17 18:00' as datetime)
    union all select 28, 29, cast('2019-03-17 18:00' as datetime)
) data

select * from #tab

--  NILH1   NILH2  DateStamp
--  --------------------------------------
--  1       2      2019-03-17 18:00:00.000
--  2       3      2019-03-17 18:00:00.000
--  3       44     2019-03-17 18:00:00.000  
--  4       5      2019-06-17 18:00:00.000  <-- invalid timestamp
--  28      6      2019-03-17 18:00:00.000

您可以使用 CTE：

;with SUMS as
(
    SELECT
        SUM(CASE WHEN NILH1 <= 25 THEN NILH1 ELSE 0 END) as NILH1SUM,
        SUM(CASE WHEN NILH2 <= 25 THEN NILH2 ELSE 0 END) as NILH2SUM
    FROM #tab
    WHERE DateStamp BETWEEN '2019-03-17 08:00' AND '2019-04-17 08:00'
)
select
    NILH1SUM as NILH1SUM,
    NILH2SUM as NILH2SUM,
    NILH1SUM + NILH2SUM as TOTAL
from
    SUMS

-- NILH1SUM NILH2SUM TOTAL
-- -----------------------
-- 6        11        17

如何获得多个 SUM 语句的总数

How to get a total for multiple SUM statements

sql

tsql

sql-server

aggregate-functions

sql-server-2008