In PostGIS I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (http://postgis.refractions.net/documentation/manual-2.1SVN/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work.

I'm not good at SQL. I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.

In PostGIS I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (https://postgis.net/docs/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work.

I'm not good at SQL. I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.

In postgis I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (http://postgis.refractions.net/documentation/manual-2.1SVN/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work, thanks for any advice - I'm not good at sql stuff, I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.

In PostGIS I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (http://postgis.refractions.net/documentation/manual-2.1SVN/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work.

I'm not good at SQL. I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.

In postgis I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (http://postgis.refractions.net/documentation/manual-2.1SVN/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work, thanks for any advice - I'm not good at sql stuff, I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.

Thanks for response

In postgis I have 2 layers:'lines' (multilinestring, public, gid, geom) and 'polygons' (multipolygon, public, gid, geom). I try to find how to convert them to multipoint (or point). I suspect that ST_CollectionExtract (http://postgis.refractions.net/documentation/manual-2.1SVN/ST_CollectionExtract.html) can do that, but I didn't find any sql example; I tried sth like:

SELECT ST_CollectionExtract (public.polygons as geom,1)

but it doesn't work, thanks for any advice - I'm not good at sql stuff, I usually try to find some sql example that uses all those things like gid, geom, table_name, column_name etc.