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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Finding overlapping time periods - suggestions please
Finding overlapping time periods - suggestions pleaseHi,
I remember reading a similar problem in 'Joe Celko's SQL Puzzles & Answers'. The solution he provided was excellent and very innovative, but I can't recollect the method right now. See if you can find it somewhere; it might be on the web. I think it was about Doctors' overlapping duty times in a hospital.
Regards,
Charu.
-----Original Message-----
From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com]On Behalf Of
babette.turnerunderwood_at_hrdc-drhc.gc.ca
Sent: 31 October 2003 23:55
To: Multiple recipients of list ORACLE-L
Subject: Finding overlapping time periods - suggestions please
I was wondering if anyone had the need to find overlapping time periods and how to identify them efficiently.
Here is the scenario:
Elapsed minutes refer to the actual “clock” time either spent on a given task. Thus an activity that started at 9:00 am and finished at 11:00 am on the same day is said to have 120 elapsed minutes.
If one task overlaps another (either completely or partially with another task), then the tasks are said to be “multitasked”. In that case the system will store the portion of the elapsed time that was multitasked as “elapsed multitask minutes” and the portion of the time that was not overlapped as “elapsed single minutes”. In addition, for the portion of time that two or more activities were simultaneously taking place; their time will be divided by the number of simultaneous activities and stored as “prorated multi minutes”. The sum of Elapsed Single Minutes and Prorated Minutes will equal the actual clock time that a vehicle was active.
The following example should help to illustrate these concepts. In the table below a list of fictitious activities for a vehicle are shown in addition to how the time is allocated to the various measures:
Activity Start Time End Time Elapsed Minutes Elapsed Multitask Minutes Elapsed Single Minutes Prorated Multi Minutes Prorated Minutes 1 10:00 12:00 120 60 60 25 85 3 11:00 13:00 120 120 0 55 55 4 11:30 13:30 120 90 30 40 70 7 13:30 16:00 150 0 150 0 150 Totals 510 270 240 120 360The vehicle was active from 10:00 to 16:00, a total of 6 hours (360 minutes) which is equal to the total of Prorated Minutes.
The vehicle performed 8 ½ hours (510 minutes) of work during that 6-hour time span. This can be arrived at by adding the total of Elapsed Multitask Minutes (270) + the total of Elapsed Single Minutes (240).
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Author: Charu Joshi
INET: joshic_at_mahindrabt.com
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