[postgis-users] creating linestrings from points, complexish linestrings

[Martin Davis]

First of all, don't you need some kind of ordering attribute on the 
points?  Otherwise how would you determine the order the points occur in 
the linestring?

Rhys Stewart wrote:
> Hi all,
>
> I have the following table:
>
> CREATE TABLE tmp.children
> (
>  parish character varying(50),
>  pointnumber numeric(18),
>  parent character varying(254),
>  devicetype character varying(50),
>  coordfix geometry
> )
>
> The table holds a parent-child relationship in columns pointnumber and 
> parent.
> i.e., if a point has a parent the pointnumber  for that parent is in
> the parent field.
> The devicetype can either be Start, Inter or End. The only time a row
> has no parent is when its devicetype is start. There can be any number
> of inters.
>
> I would like to create one linestring encompassing an entire
> start-inter-end sequence and am having trouble wrapping my brain
> around it.
>
>
> Any suggestions?
>
>
> Thanks
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-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022