[GRASS-dev] Some v.db.addtable and [v.]category confusion

[Markus Neteler]

Hi,

I got a second time trapped by the problem that v.db.addtable
(no longer?) adds rows into the new attribute table. I suspect
that a v.category call is needed before v.to.db (at the end
of the script). But v.category would write into a new map
and then handling gets messy.

Example:

# Spearfish
g.copy vect=fields,myfields
v.db.addtable myfields layer=2 col="polynum integer"
v.category myfields op=report layer=2
LAYER/TABLE 1/myfields:
type       count        min        max
point          0          0          0
line           0          0          0
boundary       0          0          0
centroid      63          1         63
area           0          0          0
all           63          1         63

-> it's not clear from this output that it is only layer 1!!
(try: v.category myfields op=report layer=33
 which gives the same result)

So: in reality there aren't any categories yet on layer 2.
v.category myfields out=myfields_new op=add layer=2
v.db.select myfields_new layer=2
cat|polynum

Nothing again. I think that there should be a row for each
vector now but it isn't. Due to that I cannot use v.db.update
on it to insert new polynum values.

?

Markus