Dan,
This is not really difficult, just long:
make sure your two tables have a common field that will link all records in the two
tables (e.g. have a field in each table with only 1's in them for instance - I'll call
them "common").
Then use the following query:
Select TableA.Identifier,TableB.Identifier,
Distance(CentroidX(TableA.Obj),Centroidy(TableA.Obj),centroidx(TableB.Obj),centroidy(TableB.Obj),"km")
from TableA, TableB
where TableA.common=TableB.common and
Distance(CentroidX(TableA.Obj),Centroidy(TableA.Obj),centroidx(TableB.Obj),centroidy(TableB.Obj),"km")
<50
into Selection
The first part of the WHERE clause links all records in the two tables (there is
probably a more elegant way to do this, but this way works), while the second parts
checks whether the distance between the points is less than 50 km.
The SELECT clause gives you the identifiers for the matching pairs and the distance
betwen them.
Good luck
Mark Knudsen
__________________________________________________________________
Veitch Lister Consulting Pty Ltd Phone: +61 3 9427 7400
Suite 14 663 Victoria Street Fax: +61 3 9427 0481
ABBOTSFORD VIC 3067 email: [EMAIL PROTECTED]
__________________________________________________________________
-----Original Message-----
From: [EMAIL PROTECTED]
Sent: Wednesday, March 01, 2000 8:03 AM
To: [EMAIL PROTECTED]
Subject: MI Distance Query
I have two layers or two databases in which one of them contains over 600 points
(lets call it table A) and the other about 200 points (table B). I would like to
select from table A all the points that are at least within a 50 km radius from
each point in table B. In other words I would like to have a list of the records
in table A that are at least 50 km of a record in table B and in that list also
indicate the record from table B that matched. Can this be done in a simple
query? What would be the easiest way to do this? Any help is appreciated.
Thanks,
Dan Page
[EMAIL PROTECTED]
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
