[..] Nikos A:
> >> > Also, there is a single reference on (how to create a new?) vector > >> > attribute table layer(s) in the "Intro: "Using v.db.connect > >> > connections between layers and attribute tables can be listed or > >> > maintained.". Markus N: > >> ... I don't fully understand where to add what... > > Maybe I was wrong -- perhaps it is better to add a clear instructive > > example in the "v.db.connect" manual itself (where, also, nothing is > > mentioned regarding new layers). > >> > Maybe we can add in the manual of "v.db.connect" the word "layer" as a > >> > Keyword > >> Yes, done so: > >> http://grass.osgeo.org/grass70/manuals/keywords.html > >> Layer > >> v.category, v.db.connect > >> > and an example on how to create/connect to a *new* (empty) layer? Markus Metz wrote: > A new layer is created by adding categories in the new layer to vector > features. This has nothing to do with database connections. Therefore > you can by definition not create an empty layer. > In short, > create a new layer with v.category connect an existing table to a vector > layer with db.connect (the layer does not need to exist, a new layer will > not be created) create a new table for an existing layer with v.db.addtable Perfect, scratch all the rest then. Thank you Markus for clearing-up once again! Still, I find it counter-intuitive that it's required to create a new vector map to achieve that. --%<--- v.category in=wrs2_tiles_of_interest_testing@PERMANENT layer=2 option=add ERROR: Output vector wasn't entered --->%-- An ignorant like me will probably ask himself: I need a new layer in this map. Why do I need to create an extra map? For the records, related posts in <http://lists.osgeo.org/pipermail/grass-user/2013-May/068131.html> > >> Could you provide one for me to add it? > > It works (also) for example by .. > > # add new layer by... ! > > v.db.addtable wrs2_tiles_of_interest_testing layer=2 > This does not add a new layer, it adds only a new connection. The > newly added table would be empty if there are no categories in the > given vector layer. O-K > > The other way, using "v.db.connect" (in G7) gives me the WARNING(s): [stuff deleted] > v.db.connect connects an existing table. If the specified table does > not exist, you get this warning, nothing wrong with that. > > Though, it creates the layer=3: [stuff deleted] > No, v.db.connect does not create a new layer, only a new connection. > You need to check with v.category if a layer exists. You can, however, > connect a table to a nonexisting layer with v.db.connect. Good. But maybe we need to make it more clear why it is possible to create a (new) connection to something that does not exist yet? The WARNINGS are correct. Still, connecting to something non-existing is rather confusing. > This is all illustrated in the picture mentioned earlier in this thread [0]. > [0] > http://grasswiki.osgeo.org/wiki/Vector_Database_Management#Grass_vector_man > agement_model Cheers, Nikos _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user