Question

我正在尝试利用自我加入来计算在每个代码清单中每日滚动1年平均值。以下代码似乎提供了所有代码和日期的平均值，而不是提供针对每个代码和日期更改的唯一结果。（换句话说，输出中的第三列始终相同，但每行实际上应该是唯一的）。

这里有什么建议吗？谢谢

SELECT [Ticker], [Date],
(SELECT AVG(T.[Close])
FROM [intradayOHLC_Selected_Closing_Prices_Staging] AS T
JOIN [intradayOHLC_Selected_Closing_Prices_Staging] AS O2
ON T.[Ticker] = O2.[Ticker]
AND T.[Date] between O2.[Date 250 Days Ago] AND O2.[Date])
FROM [intradayOHLC_Selected_Closing_Prices_Staging] AS O2

Answer 1

子查询中有一个额外的JOIN。这不是必需的。你只需要一个相关的子查询。

SELECT [Ticker], [Date],
       (SELECT AVG(T.[Close])
        FROM [intradayOHLC_Selected_Closing_Prices_Staging] AS T
        WHERE T.[Ticker] = O2.[Ticker] AND
              T.[Date] between O2.[Date 250 Days Ago] AND O2.[Date]
       ) as RollingAverage
FROM [intradayOHLC_Selected_Closing_Prices_Staging] AS O2;

如何使用自联接来计算历史滚动平均值

1 个答案: