OleDb选择命令返回空列

Question

我的数据库中有两个已保存的查询，名为Free_Cash_Flow和Quarterly_Growth_Rates。它们显示在这里：

Free_Cash_Flow：

Quarterly_Growth_Rates：

当我使用此代码时：

SELECT * _
FROM Free_Cash_Flow AS C _
INNER JOIN Quarterly_Growth_Rates AS G _
ON (C.Ticker = G.Ticker) AND ((IIF(C.Period = 4, C.Year + 1, C.Year)) = G.Year) AND ((IIF(C.Period = 4, 1, C.Period + 1)) = G.Qtr)

返回：

列Free_Cash_Flow为空。但正如您在Free_Cash_Flow表中看到的那样，该列中有数据。为什么不被拉进新桌子？我使用类似格式的其他表运行此查询，一切都很好。有什么建议吗？

其他信息

我想补充说，Free_Cash_Flow列是使用其各自保存的查询的SQL语句中的公式填充的。我想这可能与我的问题有关。我真的被困在这里，我迫切需要解决这个问题。

以下是包含用于Free_Cash_Flow保存查询的SQL语句的代码：

变量：

Dim Calculation = “Free_Cash_Flow”

Dim Formula = “(SELECT (SUM(su.Net_Cash_Flow_Operating) - SUM(su.Capital_Expenditures)) _
FROM (SELECT Ticker, [Year], Period, Net_Cash_Flow_Operating, Capital_Expenditures _
FROM Cash_Flow_Statements UNION ALL SELECT Ticker, [Year] + 1, Period - 4, Net_Cash_Flow_Operating, Capital_Expenditures _
FROM Cash_Flow_Statements) su _
WHERE su.Ticker = c.Ticker AND su.[Year] = c.[Year] AND (su.Period Between c.Period - 3 And c.Period))”

Dim Where_Statement = "WHERE i.Period < 5"

SQL语句：

"CREATE PROC " & Calculation & " AS SELECT i.Ticker, i.[Year], i.Period, " & Formula & " AS " & Calculation & " _
FROM (Income_Statements AS i _
INNER JOIN Balance_Sheets AS b _
ON (i.Ticker = b.Ticker) AND (i.[Year] = b.[Year]) AND (i.Period = b.Period)) _
INNER JOIN Cash_Flow_Statements AS c ON (b.Ticker = c.Ticker) AND (b.[Year] = c.[Year]) AND (b.Period = c.Period) " & Where_Statement & ""

Answer 1

不要特别知道原因，但使用“*”通常不是首选，但如果您明确查询指定的列，则可能有更好/正确的答案，例如

select 
      C.Ticker,
      C.Year,
      C.Period,
      C.Free_Cash_Flow,
      G.Year as GrowthYear,
      G.Period as GrowthPeriod 
   from ....

可能会感到困惑，因为表名与列相同并忽略它。通过分别用“C”和“G”别名限定列，可能会做你想要的。

Answer 2

这可能与您的JOIN无关。我想知道Free_Cash_Flow是否属于OLEDB不理解的类型。看起来它在Open Office中作为货币价值，对吧？你知道OLEDB可以看到这个价值的事实吗？尝试更简单的查询，如

SELECT C.Free_Cash_Flow FROM Free_Cash_Flow AS C

并查看是否会出现任何问题。

Answer 3

您是否尝试将最后一部分更改为WHERE并查看返回的内容？

WHERE ((IIF(C.Period = 4, C.Year + 1, C.Year)) = G.Year) AND
      ((IIF(C.Period = 4, 1, C.Period + 1)) = G.Qtr)

Answer 4

您需要指定重命名时所需的列，如C＆amp; G下面：

SELECT C.*, G.* _
FROM Free_Cash_Flow AS C _
INNER JOIN Quarterly_Growth_Rates AS G _
ON (C.Ticker = G.Ticker) AND ((IIF(C.Period = 4, C.Year + 1, C.Year)) = G.Year) AND ((IIF(C.Period = 4, 1, C.Period + 1)) = G.Qtr)

Answer 5

理论上，没有理由不这样做，除了列名与表名相同这一事实。也许您的数据库引擎对此感到困惑，请尝试重命名。

Answer 6

尝试替换下面的表名，并检查如果该列也没有出现，则Quarterly_Growth_Rates列是否即将到来，那么它可能是名称相同的问题。

SELECT * _ FROM Quarterly_Growth_Rates AS G _ INNER JOIN Free_Cash_Flow AS C _ON（G.Ticker = C.Ticker）AND（G.Year =（IIF（C.Period = 4，C.Year + 1，C.Year）））AND（G .Qtr =（IIF（C.Period = 4,1，C.Period + 1）））