使用LEFT JOIN和INNER JOIN的MS-ACCESS

Question

SELECT
U.[Current Month], 
U.[Security Name],
U.[CM Return],
(P1.[Return] * P2.[Return] * P3.[Return] * P4.[Return] * P5.[Return] * P6.[Return] * P7.[Return]) AS [7 Month Return],
(P1.[Return] * P2.[Return] * P3.[Return] * P4.[Return] * P5.[Return] * P6.[Return] * P7.[Return] * P8.[Return]) AS [8 Month Return],
(P1.[Return] * P2.[Return] * P3.[Return] * P4.[Return] * P5.[Return] * P6.[Return] * P7.[Return] * P8.[Return] * P9.[Return]) AS [9 Month Return],
(P1.[Return] * P2.[Return] * P3.[Return] * P4.[Return] * P5.[Return] * P6.[Return] * P7.[Return] * P8.[Return] * P9.[Return] * P10.[Return]) AS [10 Month Return],
(P1.[Return] * P2.[Return] * P3.[Return] * P4.[Return] * P5.[Return] * P6.[Return] * P7.[Return] * P8.[Return] * P9.[Return] * P10.[Return] * P11.[Return]) AS [11 Month Return]
FROM ((((((((((((
[Prior Month Returns Tbl] AS U
INNER JOIN [Securities] AS S ON U.[Security Name] = S.[Security Name])
LEFT JOIN [Data 9 17 Monthly] AS P1 ON P1.[Security ID] = S.[ID] AND P1.[Date Month] = DateAdd("m",-1,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P2 ON P2.[Security ID] = S.[ID] AND P2.[Date Month] = DateAdd("m",-2,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P3 ON P3.[Security ID] = S.[ID] AND P3.[Date Month] = DateAdd("m",-3,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P4 ON P4.[Security ID] = S.[ID] AND P4.[Date Month] = DateAdd("m",-4,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P5 ON P5.[Security ID] = S.[ID] AND P5.[Date Month] = DateAdd("m",-5,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P6 ON P6.[Security ID] = S.[ID] AND P6.[Date Month] = DateAdd("m",-6,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P7 ON P7.[Security ID] = S.[ID] AND P7.[Date Month] = DateAdd("m",-7,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P8 ON P8.[Security ID] = S.[ID] AND P8.[Date Month] = DateAdd("m",-8,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P9 ON P9.[Security ID] = S.[ID] AND P9.[Date Month] = DateAdd("m",-9,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P10 ON P10.[Security ID] = S.[ID] AND P10.[Date Month] = DateAdd("m",-10,U.[Current Month]))
LEFT JOIN [Data 9 17 Monthly] AS P11 ON P11.[Security ID] = S.[ID] AND P11.[Date Month] = DateAdd("m",-11,U.[Current Month]))
WHERE S.ID = 14

上面是我要执行的MS-ACCESS查询。 对于安全ID 14，我想做的事情很简单。我想在[Prior Month Return Tbl]中计算当前月的[Data 9至17 Monthly]表中前7至11个月的收益的乘积。 如果我使用内部联接，该查询工作正常，但如果[数据9至17月度]中没有全部之前的11个月记录，则它将省略结果，因此这就是为什么我使用左联接但我得到联接表达式的错误不支持。 请帮忙。 我知道此查询在t-sql中可以正常工作。 我应该怎么做才能在MS-Access中使用此查询？

Answer 1

在外部联接中，MS Access不支持两个表之间的条件。 我认为这是一个非常奇怪的限制。

您可以使用子查询来解决它。 这是一个例子：

LEFT JOIN
(SELECT P1.*
 FROM [Data 9 17 Monthly] AS P1
 WHERE P1.[Date Month] = DateAdd("m",-1,U.[Current Month]))
) as P1
ON P1.[Security ID] = S.[ID]

或者，您可以使用条件聚合将所有数据合并到单个行中：

LEFT JOIN
(SELECT [Security ID],
        MAX(IIF(P1.[Date Month] = DateAdd("m", -1, U.[Current Month])), [RETURN], 1) as Return_01,
        MAX(IIF(P1.[Date Month] = DateAdd("m", -2, U.[Current Month])), [RETURN], 1) as Return_02,
        . . .
        MAX(IIF(P1.[Date Month] = DateAdd("m", -12, U.[Current Month])), [RETURN], 1) as Return_12
) as P
ON P.[Security ID] = S.[ID]

然后根据需要调整外部SELECT 。

或者，您可以升级到更符合ANSI的数据库。