DateAdd中的SQL-If语句

我对SQL非常陌生，但我非常喜欢它，并希望在这方面做得更好

在我的代码中，我将3个表合并在一起，然后为合并创建几列。我已经创建了一列“DaysOfStock”，并希望将每列中的数字添加到当前日期。问题是“DaysOfStock”是一个“if”函数，我不知道如何将它添加到“DayAdd”函数中。下面是我遇到问题的代码部分

SELECT Cust.Article,
    IsNull(stock.StockQuantity,0) StockQuantity,
    IsNull(orders.OpenQty,0) OpenOrders,
    IsNull(usage.[3MonUsage], 0) [3MonUsage], IsNull(usage.EAU, 0) [EAU],
    ROUND(IsNull(usage.EAU, 0)/366,0) DailyUsage,
    CASE WHEN IsNull(usage.EAU, 0)/366 = 0 THEN ROUND(IsNull(stock.StockQuantity,0)/(IsNull(orders.OpenQty, 0)/366),2)
    ELSE ROUND(IsNull(stock.StockQuantity,0)/(IsNull(usage.EAU, 0)/366),2) END AS DaysOfStock
    DateAdd(day, **DaysOfStock**, GetDate())
FROM TeslaArts 
        LEFT OUTER JOIN usage ON CustArts.Article = usage.Article
        LEFT OUTER JOIN stock ON CustArts.Article = stock.Article
        LEFT OUTER JOIN orders ON CustArts.Article = orders.Article
WHERE (orders.OpenQty > 0 AND usage.[3MonUsage] > 0)
    OR (orders.OpenQty = 0 AND usage.[3MonUsage] > 0)
    OR (orders.OpenQty > 0 AND usage.[3MonUsage] = 0)

如果有什么不清楚的地方，请告诉我。 提前谢谢你的帮助。

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-alex

嗯，很简单，只要重复相同的代码：

SELECT Cust.Article,
    IsNull(stock.StockQuantity,0) StockQuantity,
    IsNull(orders.OpenQty,0) OpenOrders,
    IsNull(usage.[3MonUsage], 0) [3MonUsage], IsNull(usage.EAU, 0) [EAU],
    ROUND(IsNull(usage.EAU, 0)/366,0) DailyUsage,
    CASE WHEN IsNull(usage.EAU, 0)/366 = 0 THEN ROUND(IsNull(stock.StockQuantity,0)/(IsNull(orders.OpenQty, 0)/366),2)
    ELSE ROUND(IsNull(stock.StockQuantity,0)/(IsNull(usage.EAU, 0)/366),2) END AS DaysOfStock,
    DateAdd(day,
           CASE WHEN IsNull(usage.EAU, 0)/366 = 0 THEN
               ROUND(IsNull(stock.StockQuantity,0)/(IsNull(orders.OpenQty, 0)/366),2)
          ELSE
              ROUND(IsNull(stock.StockQuantity,0)/(IsNull(usage.EAU, 0)/366),2)
          END,
          GetDate()) AS ProjectedDate
FROM TeslaArts 
        LEFT OUTER JOIN usage ON CustArts.Article = usage.Article
        LEFT OUTER JOIN stock ON CustArts.Article = stock.Article
        LEFT OUTER JOIN orders ON CustArts.Article = orders.Article
WHERE (orders.OpenQty > 0 AND usage.[3MonUsage] > 0)
    OR (orders.OpenQty = 0 AND usage.[3MonUsage] > 0)
    OR (orders.OpenQty > 0 AND usage.[3MonUsage] = 0)