作为子查询一部分的 SQL 列的总计运行

Question

这里有很多帖子描述了如何进行运行总计，但我遇到的情况是运行总计需要是使用子查询计算的列的总计（这意味着我当前的 ORDER BY 导致查询失败）

我有一个 table 显示每个时间段的金额，如下所示：

TimePeriod   Amount
2022-03-31   396
2022-03-31   16
2022-03-31   84
2021-12-31   842
2021-12-31   57
2021-09-30   652
2021-09-30   25
2021-09-30   173

在我的查询中，我需要找到每个时间段占总数的百分比。我所做的是：

SELECT 
    TimePeriod,
    SUM(Amount) AS 'Total Per Period', 
    CAST( ROUND( SUM(Amount)/(SELECT SUM(Amount) FROM MyDatabase.MyTable),3) AS DECIMAL(12,3)) AS 'Percentage of Total'
FROM
    MyDatabase.MyTable
GROUP BY
    TimePeriod
ORDER BY
    TimePeriod DESC

这给了我一个正确的输出，像这样：

TimePeriod   Total per Period   Percentage of total
2022-03-31   496                0.221
2021-12-31   899                0.400
2021-09-30   850                0.379

我想要做的是在 'Percentage of total' 列中添加一个运行总数，例如：

TimePeriod   Total per Period   Percentage of total   Running total percentage
2022-03-31   496                0.221                 0.221
2021-12-31   899                0.400                 0.621
2021-09-30   850                0.379                 1.000

我试图做的是首先将它添加到第一个 SELECT 子句中，但这不起作用，因为它是一个只存在于我的查询中的列。然后我尝试对 select 做一个 select，像这样：

SELECT
    TimePeriod,
    'Total Per Period',
    'Percentage of Total',
    SUM('Percentage of Total') OVER (ORDER BY TimePeriod)
FROM
    (SELECT 
        TimePeriod,
        SUM(Amount) AS 'Total Per Period', 
        CAST( ROUND( SUM(Amount)/(SELECT SUM(Amount) FROM MyDatabase.MyTable),3) AS DECIMAL(12,3)) AS 'Percentage of Total'
    FROM
        MyDatabase.MyTable
    GROUP BY
        TimePeriod
    ORDER BY
        TimePeriod DESC)

这会抛出错误，指出子查询中不允许使用最后一个 ORDER BY。相反，删除 ORDER BY 表示语法不正确。我猜问题是我有一个引用子查询结果的子查询，但我不确定如何解决这个问题。我的查询中似乎缺少什么？

Answer 1

您可能需要使用[]来包含列名而不是'，这意味着字符串值，我们还需要给子查询一个别名。

SELECT
    TimePeriod,
    [Total Per Period],
    [Percentage of Total],
    SUM([Percentage of Total]) OVER (ORDER BY TimePeriod)
FROM
    (SELECT 
        TimePeriod,
        SUM(Amount) AS 'Total Per Period', 
        CAST( ROUND( SUM(Amount)/(SELECT SUM(Amount) FROM MyDatabase.MyTable),3) AS DECIMAL(12,3)) AS 'Percentage of Total'
    FROM
        MyDatabase.MyTable
    GROUP BY
        TimePeriod) t1
ORDER BY
    TimePeriod DESC

Answer 2

您有一些语法错误，还有一些需要改进的地方：

正如另一个答案中提到的，派生的 table 需要一个别名
如有必要，请使用 [] 引用列名（最好一开始就不要使用此类列名）。
您不能在派生的 table 或子查询中包含 ORDER BY，这样做也没有意义。
您可以用 SUM(SUM) OVER () window 函数替换 SELECT SUM 子查询。
如果 TimePeriod 可能有重复，运行总计 window 函数必须有 ROWS UNBOUNDED PRECEDING。它也更快。
因为您是按 TimePeriod DESC 排序的，所以运行总计的顺序与主 ORDER BY 相同但使用 ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING 可能会更快得出相同的结果。好处是查询计划中少了一种排序。

SELECT
    TimePeriod,
    [Total Per Period],
    [Percentage of Total],
    SUM([Percentage of Total]) OVER (ORDER BY TimePeriod DESC ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
FROM
    (SELECT 
        TimePeriod,
        SUM(Amount) AS [Total Per Period],
        CAST( ROUND( SUM(Amount) / SUM(SUM(Amount)) OVER () , 3) AS DECIMAL(12,3)) AS [Percentage of Total]
    FROM
        MyDatabase.MyTable
    GROUP BY
        TimePeriod
) t
ORDER BY
    TimePeriod DESC;

进一步的改进是将整个事情合并为一个级别：

SELECT
    TimePeriod,
    SUM(Amount) AS [Total Per Period],
    CAST( ROUND(
            SUM(Amount) /
            SUM(SUM(Amount)) OVER ()
          , 3) AS DECIMAL(12,3)) AS [Percentage of Total],
    CAST( ROUND(
            SUM(SUM(Amount)) OVER (ORDER BY TimePeriod DESC ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING) /
            SUM(SUM(Amount)) OVER ()
          , 3) AS DECIMAL(12,3))
FROM
    MyDatabase.MyTable
GROUP BY
    TimePeriod
ORDER BY
    TimePeriod DESC;

请注意，由于四舍五入，结果可能略有不同。

SQL Fiddle

Answer 3

这是我对你的问题的解决方案。我用Oracle解决了。

with flo as (
    select
      timeperiod, 
      sum(amount) as amount,
      cast((sum(amount) / (select sum(amount) from da ))as decimal(10,6)) *100.0 as percent_of_total
    from  yourtable
    group by timeperiod
)
select
  timeperiod,
  amount,
  percent_of_total,
  sum(percent_of_total) over (order by timeperiod desc ) as running
from flo;

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