[postgis-users] Obtaining an address closest based on x/y coordinate pair
TMitchell at lignum.com
Mon Mar 22 10:19:04 PST 2004
> I have been trying desperately but unsuccessfully to get the address
Unless I'm missing something, this should be straightforward with the use
of a couple more functions. Don't be scared of them, they'll help you a
lot :) Specifically, you want to use the Distance() function in PostGIS.
It takes in two geometry fields and will compute the distance for you.
If there are way you can have the coordinates that the user enters get put
into a postgis table in a geometry column? If you can get that setup it
will make discussion even easier. Let's pretend that you get that working
and that your point is in a table called UserPoint and it has a the_geom
field. Here is how you would do your query:
str_num ||" "|| name AS address
Distance(UserPoint.the_geom, address.the_geom) < 1000;
-You don't need to a UserPoint table with a geometry field, you could
create a string that represents the geometry too. Let us know if you need
help doing this.
-The "< 1000" is the distance threshold I set - change it to whatever you
-If you have a lot of points, this probably won't be very efficient. But
try it out with a few pieces first to see. :)
-When you are ready to optimize things, let us know and we'll introduce
you to && operator and Expand() function.
Is this helpful?
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