SQL 使用 UNION ALL 前一行结果的表达式

Question

我有这两个 tables:

Collect: Date, Rute, Value_Collected...
Records: Date, Rute, Value, Type...

其他列与本例无关。所以我有这个工作代码：

SELECT
Totals.Date                             AS [Date],
Sum(Totals.Collected)                   AS [Collect],
Sum(Totals.Injected)                    AS [Injections],
Sum(Totals.Spent)                       AS [Expenses],
([Collect] + [Injections]) - [Expenses] AS [Total Day]

FROM (
    SELECT
    Records.Date                        AS [Date],
    0                                   AS [Collected],
    Sum(IIF(Type =  3,Records.Value,0)) AS [Injected],
    Sum(IIF(Type <> 3,Records.Value,0)) AS [Spent]
    FROM Records GROUP BY Records.Date

    UNION ALL

    SELECT
    Collect.Date                 AS [Date],
    Sum(Collect.Value_Collected) AS [Collected],
    0                            AS [Injected],
    0                            AS [Spent]
    FROM Collect GROUP BY Collect.Date
) AS Totals GROUP BY Totals.Date

这给了我这个结果：

|Date       |Collect    |Injections  |Expenses   |Total Day
-----------------------------------------------------------
|5/09/2016  |.000   |[=13=]           |[=13=]         |.000 |
|6/09/2016  |.000   |[=13=]           |[=13=]         |.000 |
|7/09/2016  |.000   |[=13=]           |[=13=]         |.000 |
|11/09/2016 |2.000  |[=13=]           |[=13=]         |2.000|
|14/09/2016 |.000    |[=13=]           |[=13=]         |.000  |
|16/09/2016 |0.000  |[=13=]           |.000     |.000 |
|30/09/2016 |[=13=]        |.000      |.000    |.000 |
-----------------------------------------------------------

现在没问题，但是 [Total Day] 列的公式必须像这样计算 ([Total Day Of Last Row] + [Collect] + [Injections]) - [Expenses] 而不是 ([Collect] + [Injections]) - [Expenses] 才能得到我想要的结果：

|Date       |Collect      |Injections  |Expenses   |Total Day
-------------------------------------------------------------
|5/09/2016  |.000      |[=14=]          |[=14=]         |.000 |
|6/09/2016  |.000      |[=14=]          |[=14=]         |.000 |
|7/09/2016  |.000      |[=14=]          |[=14=]         |.000 |
|11/09/2016 |2.000     |[=14=]          |[=14=]         |2.000|
|14/09/2016 |.000       |[=14=]          |[=14=]         |9.000|
|16/09/2016 |0.000     |[=14=]          |.000     |2.000|
|30/09/2016 |[=14=]           |.000     |.000    |7.000|
-------------------------------------------------------------

但是我不知道如何获取前一行的[Total Day]来计算当前行的[Total Day]。如果我尝试运行 [Totals] 的子查询，它会给我一个错误，因为它找不到 table Totals。我认为这是因为它不是 "real" table，但我真的不知道如何实现它。非常感谢任何帮助。

PS：列的名称和 tables 最初是西班牙语，但出于某种目的进行了翻译，以便您可以理解我需要完成的工作。

Answer 1

从本质上讲，您需要按渐进日期计算各个字段的累计总和，这可以通过相关总和聚合子查询来处理。唯一的挑战是 MS Access 没有像其他 SQL 方言那样的 window 函数来重用派生的 table 查询。所以你需要在子查询中重复 union derived table:

SELECT main.Date, main.Collected AS [Collect], 
       main.Injected As [Injections], main.Spent As [Expenses],
       Ccur((SELECT Sum(sub.Collected) + Sum(sub.Injected) - Sum(sub.Spent) 
             FROM 
               (SELECT Records.Date AS [Date], 0 AS [Collected],
                       Sum(IIF(Type =  3,Records.Value,0)) AS [Injected],
                       Sum(IIF(Type <> 3,Records.Value,0)) AS [Spent]
                FROM Records GROUP BY Records.Date
                UNION ALL
                SELECT Collect.Date AS [Date],
                       Sum(Collect.Value_Collected) AS [Collected],
                       0 AS [Injected],
                       0 AS [Spent]
                FROM Collect GROUP BY Collect.Date
                ) As sub
             WHERE sub.Date <= main.Date)) As [Total Day]

FROM
  (SELECT Records.Date AS [Date], 0 AS [Collected],
          Sum(IIF(Type =  3,Records.Value,0)) AS [Injected],
          Sum(IIF(Type <> 3,Records.Value,0)) AS [Spent]
   FROM Records GROUP BY Records.Date
   UNION ALL
   SELECT Collect.Date AS [Date],
         Sum(Collect.Value_Collected) AS [Collected],
         0 AS [Injected],
         0 AS [Spent]
   FROM Collect GROUP BY Collect.Date
  ) As main

幸运的是，MS Access 确实维护了存储的查询对象，您可以在其中将 UNION 查询保存为单独的查询，并在新查询中引用它以获得更短的脚本：

SELECT main.Date, main.Collected As [Collect], 
       main.Injected As Injections, main.Spent As Expenses,  
       Ccur((SELECT Sum(sub.Collected) + Sum(sub.Injected) - Sum(sub.Spent) 
             FROM RecordsUnionQ As sub
             WHERE sub.Date <= main.Date)) As [Total Day]
FROM RecordsUnionQ As main

使用支持CTE的SQLite 3，可以使用WITH()子句来保持联合查询，避免在子查询中重复。 CTE 仅在 SQL 语句期间充当临时视图。

WITH main AS
  (SELECT Records.Date AS [Date], 0 AS [Collected],
          Sum(IIF(Type =  3,Records.Value,0)) AS [Injected],
          Sum(IIF(Type <> 3,Records.Value,0)) AS [Spent]
   FROM Records GROUP BY Records.Date
   UNION ALL
   SELECT Collect.Date AS [Date],
         Sum(Collect.Value_Collected) AS [Collected],
         0 AS [Injected],
         0 AS [Spent]
   FROM Collect GROUP BY Collect.Date)

SELECT main.Date, main.Collected AS [Collect], 
       main.Injected As [Injections], main.Spent As [Expenses],
       Ccur((SELECT Sum(sub.Collected) + Sum(sub.Injected) - Sum(sub.Spent) 
             FROM main As sub
             WHERE sub.Date <= main.Date)) As [Total Day]
FROM main;

SQL 使用 UNION ALL 前一行结果的表达式

SQL Expressions using result of previous row of UNION ALL

sql

ms-access

union-all