ScottPletcher (10/2/2012)
dwain.c (9/26/2012)
Nice set up data Sean!Using it, I'd like to offer a slightly less verbose solution:
SELECT *, WaitTime=DATEDIFF(minute
,CAST(check_in AS TIME)
,CAST(STUFF(appt_time, 3, 0, ':') AS TIME))
FROM #CheckIn
The STUFF apparently forces the datatype to VARCHAR so minutes aren't lost.
Both solutions return negative minutes, so you may want to take that into account.
I think it needs one (semi)slight adjustment:
SELECT *, WaitTime=DATEDIFF(minute
,CAST(check_in AS TIME)
,CAST(STUFF(RIGHT('000' + CAST(appt_time AS varchar(4)), 4), 3, 0, ':') AS TIME))
FROM #CheckIn
Scott - Point taken. Yours works a lot better when there are no leading zeroes on the time component.
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.
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