获取报价的具体日期答案

【问题标题】：Get specific dates for offer获取报价的具体日期
【发布时间】：2013-08-15 09:31:58
【问题描述】：

我需要在一个 SQL 查询中获取所有优惠的具体日期。我不知道如何在这些条件下做到这一点：

如果有有效报价，我需要有效期间的开始/结束日期
如果有一个过期的报价，我需要last开始-/结束日期
如果有未来的报价，我需要first Start-/Enddates

餐桌优惠：

OfferID Name
10      Current Offer
20      Expired Offer
30      Coming Offer

餐桌优惠日期：（NULL = 无限优惠）

OfferID StartDate   EndDate
10      2000-01-01  2009-12-31
10      2010-01-01  NULL        //Need this (1.)
20      1900-01-01  1900-12-31
20      1901-01-01  1901-12-31  //Need this (2.)
30      2030-01-01  2030-12-31  //Need this (3.)
30      2031-01-01  NULL

结果应该是这样的：

OfferID Name    StartDate   EndDate
10      Current 2010-01-01  NULL
20      Expired 1901-01-01  1901-12-31
30      Coming  2030-01-01  2030-12-31

这将为我提供有效优惠 (1.)：

SELECT o.Name, d.StartDate, d.EndDate FROM Offer AS o
LEFT JOIN OfferDates AS d ON o.OfferID = d.OfferID
WHERE d.StartDate <= GETDATE() AND (d.EndDate IS NULL OR d.EndDate > GETDATE())

希望有人能帮帮我！

谢谢！

【问题讨论】：

标签： mysql sql tsql

【解决方案1】：

我成功了！

SELECT DISTINCT 
o.Name,  
ISNULL(curr.StartDate, ISNULL(fut.StartDate, hist.StartDate)) AS 'StartDate', --Only get "NOT NULL-StartDate"
ISNULL(curr.EndDate, ISNULL(fut.EndDate, hist.EndDate)) AS 'EndDate' --Only get "NOT NULL-EndDate"

FROM Offer AS o

-- Current
LEFT JOIN (SELECT * FROM OfferDates WHERE StartDate <= GETDATE() AND (EndDate IS NULL OR  EndDate > GETDATE())) AS curr ON (o.OfferID = curr.OfferID)

-- Expired
LEFT JOIN (SELECT OfferID, MAX(EndDate) AS EndDate FROM OfferDates WHERE EndDate < GETDATE()  AND EndDate IS NOT NULL GROUP BY OfferID)AS tmpHist ON (o.OfferID = tmpHist.OfferID)
LEFT JOIN (SELECT * FROM OfferDates WHERE OfferID NOT IN (SELECT OfferID FROM OfferDates WHERE EndDate >= GETDATE() OR EndDate IS NULL)) AS hist ON (tmpHist.OfferID = hist.OfferID AND tmpHist.EndDate = hist.EndDate)

-- Future
LEFT JOIN (SELECT OfferID, MIN(StartDate) AS StartDate FROM OfferDates WHERE StartDate > GETDATE() GROUP BY OfferID) AS tmpFut ON (o.OfferID = tmpFut.OfferID)
LEFT JOIN (SELECT * FROM OfferDates WHERE OfferID NOT IN (SELECT OfferID FROM OfferDates WHERE StartDate <= GETDATE())) AS fut ON (tmpFut.OfferID = o.OfferID AND tmpFut.StartDate = fut.StartDate)

【讨论】：