[postgis-users] Making a line from points

David Potts dave.potts at pinan.co.uk
Wed Sep 19 00:04:54 PDT 2007


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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