Posted by Anthony Paul on 04/20/07 13:33

Hello everyone,

There's an interesting SQL problem I've come across that I'm currently
banging my head against. Given the following table that contains item
location information populated every minute :

location_id date_created
=========== ============
5 2000-01-01 01:00 <-- Don't need
5 2000-01-01 01:01 <-- Don't need
5 2000-01-01 01:02 <-- Need
7 2000-01-01 01:03 <-- Don't need
7 2000-01-01 01:04 <-- Need
5 2000-01-01 01:05 <-- Need
2 2000-01-01 01:06 <-- Don't Need
2 2000-01-01 01:07 <-- Need
7 2000-01-01 01:08 <-- Need

how would you generate a result-set that returns the item's location
history *without* duplicating the same location if the item has been
sitting in the same room for a while. For example, the result set
should look like the following :

location_id date_created
=========== ============
5 2000-01-01 01:02
7 2000-01-01 01:04
5 2000-01-01 01:05
2 2000-01-01 01:07
7 2000-01-01 01:08

This is turning out to be a finger twister and I'm not sure if it
could be done in SQL; I may have to resort to writing a stored-proc.

Regards,

Anthony

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