Re: find overlapping address ranges

On Monday, September 16, 2002, at 08:18 PM, Martijn van Oosterhout
wrote:

> On Mon, Sep 16, 2002 at 09:45:46PM +0200, Tino Wildenhain wrote:
>> select c1.gid, c1.street, ... from cityplus c1, cityplus c2
>> where SOME_OVERLAPPING_CONDITION(c1..., c2...)
>
> Probably something like:
>
> a.streetname = b.streetname
> and a.numhigh > b.numlow
> and a.numlow < b.numhigh

Tino and Martijn, thanks for the suggestions. I'm on the right track
now. Couple more questions I would like to venture if I may...

1) In this table, fromleft toleft fromright toright are inconsistently
used: the "to" address are sometimes higher than the "from" address,
and the lefts may be odd or even and vice-versa. So I need to calculate
the numhigh and numlow before doing the comparison shown above. Can
this be done in SQL? I think it requires subquery?

2) If you could recommend a book on SQL, which one would you recommend?

Thanks,

Alex Rice, Software Developer
Architectural Research Consultants, Inc.
alrice@swcp.com
alex_rice@arc.to