INSERT INTO bar
SELECT ST_Makeline(the_geom)
FROM (SELECT the_geom FROM foo ORDER BY some_ordering_attribute) AS
my_sub_query;
The reason for the subquery is to order your points based on some
attribute ... like a timestamp.
Those ordered points are then passed to your makeline function call.
Hope this clarifies things.
-- Kevin
-------------
Kevin Neufeld
Software Developer
Refractions Research Inc.
300-1207 Douglas St.
Victoria, B.C., V8W 2E7
Phone: (250) 383-3022
Email: [EMAIL PROTECTED]
David Potts wrote:
hi List,
I am trying to make a linestring from a serries of points, I have tried
things like
update linetable set the_geom=makeline(select the_geom from points_table);
witch did'nt work, having looked at the documentation for making making
linestrings (addpoint,makeline, etc) and seen a previous example from
(http://postgis.refractions.net/pipermail/postgis-users/2005-February/006916.html)
SELECT MakeLine(the_geom) FROM ( SELECT the_geom FROM points
ORDER BY time ) foo;
I am still confused, I can't see how the last example is designed to work!
So if I have table called bar with an empty linestring geometry column and
I have another table foo with a series of valid point geometry entires,
how do I populate bar from foo?
David
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