[GRASSLIST:243] Re: add layers to vector howto?

[Kirk R. Wythers]

On Mar 18, 2006, at 7:49 PM, Hamish wrote:

>> I am looking for a "step by step" howto on adding layers to an
>> existing vector map. Any and all assistance would be much  
>> appreciated.
>
>
> start here:
>
> http://grass.gdf-hannover.de/twiki/bin/view/GRASS/GrassSixTutorial
>

Thanks Hamish. I have looked at the Wiki. Trouble is, there is very  
little specific information concerning how to create layers in the  
Wiki. However, based on what information is in the Wiki and scattered  
around in other locations, I have followed the following as a procedure:

As background I am using postgresql for attribute management.

1. both db.connect show database to be connected by pg
2. create layers with v.db.addtable
3. v.db.connect shows original vector and all new tables to be  
connected by pg

for example:

GRASS 6.1.cvs (minnesota_utm):~ > v.db.connect -p t61nr9w_tvol
Vector map <t61nr9w_tvol> is connected by:
layer <1> table <t61nr9w_tvol> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <2> table <t61nr9w_tvol_as> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <3> table <t61nr9w_tvol_bi> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <4> table <t61nr9w_tvol_ce> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <5> table <t61nr9w_tvol_japi> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <6> table <t61nr9w_tvol_nopi> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <7> table <t61nr9w_tvol_sp> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>
layer <8> table <t61nr9w_tvol_whpi> in database  
<host=localhost,dbname=kwythers> through driver <pg> with key <cat>

all seems correct

4. add some data to layers with db.execute

for example:

GRASS 6.1.cvs (minnesota_utm):~ > echo "INSERT INTO t61nr9w_tvol_whpi  
(cat,cords,mbm,poles,posts) values (2,-1,-1,-1,-1)" | db.execute

5. test to see if data is there with db.select

for example

echo "SELECT * FROM t61nr9w_tvol_as" | db.select;
cat|cords|mbm|poles|posts
40|61|-1|-1|-1
2|-1|-1|-1|-1

Again all seems correct. At this point I am thinking that the world  
is fine. The trouble begins when I try and use v.what.vect -e to  
interactively add data. If I start the gui form with d.what.vect,  
only the first layer appears in the form. There are no tabs to select  
any of the other 7 layers from. Since everything else seems to be  
working, I am thinking that the layers must be connected to the  
appropriate tables (otherwise db.select would not work), but I am  
confused as to why the d.what.vect form does not show the layer tabs.

Thanks,

Kirk