使用FRAME子句的視窗函數

--完全不需要 JOIN 或自訂 ROW_NUMBER！
--ROWS BETWEEN, 代替 ROW_NUMBER()
 SELECT *,

  AVG([C]) OVER (

    PARTITION BY [履約價], [買賣權], [到期月份(週別)]

    ORDER BY TRY_CAST([交易日期] AS DATE)

    ROWS BETWEEN 4 PRECEDING AND CURRENT ROW

  ) AS MA_5

FROM dbo.TXO_OHLC