PostGIS is very new to me, and I'm having difficulty performing an operation that probably isn't too difficult. I have vector layers each filled with the outline of a landmass through time. I want to query the distance between these landmasses for every matching timestep. I can do this manually:
select a.gid from_gid, b.gid to_gid, st_shortestline(a.geom,b.geom), st_distance(a.geom,b.geom) as distance from (select * from gavdos where year=3) as a, (select * from crete where year=3) as b;
The 'year' value ranges in integers from 0 to 21. It would be convenient to do this query using a FOR loop. I am however highly unsuccessful in doing so, the pgAdmin III SQL thing already presents an error when I say
DECLARE i integer;, thus before I am even ready to try and create a loop.
My question is if someone could give an example how I can (1) set-up the loop and (2) how to get the full output (as I suppose I need to update a table at every step in the loop..).
Thanks in advance! :-)