[postgis-users] noob question

Steve Lefevre lawpoop at gmail.com
Wed Jul 4 11:04:45 PDT 2007

Hello all -

I'm working on a database with GIS data. In my table,  I have columns for
latitude, longitude, and coordinates, which is the Postgis geometry data
type. What I would like to do is find the midpoint or 'average' for any
group of points.

I have the latitude and longitude, and then I use this syntax to create the
coordinates column value:

UPDATE table SET coords =  geometryfromtext('POINT( longitude latitude )',

( 4326 is the projection value that I understand is useful in the United

So now that I have a bunch of lats, longs, and coordinates, I need to find
the center point for any group of them. I can do a select query to get the
specific records I'm looking for, and then I can have the list of lat&long
points, or the coordinate geometry. How then do I take those rows and create
an SQL st

UPDATE table SET coords = geometryfromtext(' MULTIPOINT( $lat1 $long1,
$lat2 $long2, $lat3 $long3)', 4326)

Can I use the 'coords' geometry object instead?

"Computers are useless. They can only give you answers"
-- Pablo Picasso
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