Creating a BookingDate using a random function

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Creating a BookingDate using a random function

wafw1971

SSC Eights!

Points: 976
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February 20, 2013 at 5:18 am

#274300

I have an arrival date already in the system and I need to populate the Booking date using a random function, the booking date can be any day on or before the arrival date up to a maximum 90 days previous but it must be random the booking date cannot all be the same date.
I thought I cracked it but was wrong. Can you help?
SELECT ArrivalDate, DATEADD(day, -1 + RAND(checksum(NEWID()))-90
, ArrivalDate) AS BookingDate
FROM Bookings
ORDER BY ArrivalDate
Thanks
Wayne

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wafw1971 SSC Eights! Points: 976 More actions · Answer 1

Its alright I have figured it out:

SELECT ArrivalDate, DATEADD(day, -1 + RAND(checksum(NEWID()))*-90

, ArrivalDate) AS BookingDate

FROM Bookings

ORDER BY ArrivalDate

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 2

wafw1971 (2/20/2013)
Its alright I have figured it out:
...

DwainC already figured it out for you:

SELECT

ArrivalDate,

BookingDate = DATEADD(day,

-(1 + ABS(checksum(NEWID())) % 90),

ArrivalDate)

FROM Bookings

ORDER BY ArrivalDate

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

Dwain Camps SSC Guru Points: 86948 More actions · Answer 3

ChrisM@Work (2/20/2013)
wafw1971 (2/20/2013)
Its alright I have figured it out:
...
DwainC already figured it out for you:
SELECT
ArrivalDate,
BookingDate = DATEADD(day,
-(1 + ABS(checksum(NEWID())) % 90),
ArrivalDate)
FROM Bookings
ORDER BY ArrivalDate

I thought this looks familiar. But in the other thread his boss has taken it to the next level. 😛

My mantra: No loops! No CURSORs! No RBAR! Hoo-uh![/I]
My thought question: Have you ever been told that your query runs too fast?

My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.

Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
[url url=http://www.sqlservercentral.com/articles/St