首先,虽然您只生成一个小列表,但使用 CTE 生成顺序列表的性能非常糟糕,最好避免使用。
为此,我将使用系统表Master..spt_values
作为数字的顺序列表,但如果您担心使用未记录的系统表,那么上面的链接中还有其他方法。
我要做的第一件事是将技术人员的可用日期分成每天一行,这将允许技术人员仅在所需的部分时间可用(例如,如果您想从 6 月 18 日开始查询,则从您的表格截图到 6 月 26 日,使用您发布的查询,没有任何技术人员显示可用):
SELECT Date = DATEADD(DAY, spt.Number, ta.StartDate),
ta.TechnicianID,
ta.LapTopsPerDay
FROM tl_sb_technicianAvailability ta
INNER JOIN Master..spt_values spt
ON spt.Type = 'P'
AND spt.Number BETWEEN 0 AND DATEDIFF(DAY, ta.startDate, ta.EndDate)
This would simply turn:
TechnicianID StartDate EndDate LapTopsPerDay
1 20130620 20130624 3
进入
Date TechnicianID LapTopsPerDay
20130620 1 3
20130621 1 3
20130622 1 3
20130623 1 3
20130624 1 3
然后,您可以将此列表限制在所需的日期范围内,并总结笔记本电脑的总数,因为这在技术层面上不需要:
WITH ExplodedAvailability AS
( SELECT Date = DATEADD(DAY, spt.Number, ta.StartDate),
ta.TechnicianID,
ta.LapTopsPerDay
FROM tl_sb_technicianAvailability ta
INNER JOIN Master..spt_values spt
ON spt.Type = 'P'
AND spt.Number BETWEEN 0 AND DATEDIFF(DAY, ta.startDate, ta.EndDate)
)
SELECT Date, TotalLaptops = SUM(LapTopsPerDay)
FROM ExplodedAvailability
WHERE Date >= @StartDate
AND Date < @EndDate
GROUP BY Date;
最后,您可以 LEFT JOIN 到 bookings 表以获取每天可用的插槽
WITH ExplodedAvailability AS
( SELECT Date = DATEADD(DAY, spt.Number, ta.StartDate),
ta.TechnicianID,
ta.LapTopsPerDay
FROM tl_sb_technicianAvailability ta
INNER JOIN Master..spt_values spt
ON spt.Type = 'P'
AND spt.Number BETWEEN 0 AND DATEDIFF(DAY, ta.startDate, ta.EndDate)
), Availability AS
( SELECT Date, TotalLaptops = SUM(LapTopsPerDay)
FROM ExplodedAvailability
WHERE Date >= @StartDate
AND Date < @EndDate
GROUP BY Date
), Bookings AS
( SELECT Date, SlotsBooked = COUNT(*)
FROM tl_sb_booking
GROUP BY Date
)
SELECT Availability.Date,
Availability.TotalLaptops,
RemainingSlots = Availability.TotalLaptops - ISNULL(Bookings.SlotsBooked, 0)
FROM Availability
LEFT JOIN Bookings
ON Bookings.Date = Availability.Date;
我认为您所追求的是将预订添加到下一个可用日期,因此执行此操作的查询是:
DECLARE @UserID INT = 1;
WITH ExplodedAvailability AS
( SELECT Date = DATEADD(DAY, spt.Number, ta.StartDate),
ta.TechnicianID,
ta.LapTopsPerDay
FROM tl_sb_technicianAvailability ta
INNER JOIN Master..spt_values spt
ON spt.Type = 'P'
AND spt.Number BETWEEN 0 AND DATEDIFF(DAY, ta.startDate, ta.EndDate)
), Availability AS
( SELECT Date, TotalLaptops = SUM(LapTopsPerDay)
FROM ExplodedAvailability
WHERE Date >= CAST(GETDATE() AS DATE)
GROUP BY Date
), Bookings AS
( SELECT Date, SlotsBooked = COUNT(*)
FROM tl_sb_booking
GROUP BY Date
)
INSERT tl_sb_slotBooking (UserID, Date)
SELECT @UserID, MIN(Availability.Date)
FROM Availability
LEFT JOIN Bookings
ON Bookings.Date = Availability.Date
WHERE Availability.TotalLaptops > ISNULL(Bookings.SlotsBooked, 0)