[GRASS-user] concatenating/combining two table fields for multi-field join

GRASS GRASS user
1

Hello,
would like to make a table join based on two fields.

So suppose I have to create a new temporary join field (joinkey).

I have the fields area (C2) and value (D2), per one area these do not
repeat.

So in Excel I did for preparing the source table for the other values:
=(C2 & D2)

How can I perform the corresponding command on the command for the GRASS
table?

Thank a lot in advance,
Timmie

2

How can I perform the corresponding command on the command for the GRASS
table?

In
http://grass.osgeo.org/grass65/manuals/sql.html I found:
v.db.update vectormap column=column3 qcolumn="column1 || column2"

running the command on my data yields:

#dbmi: Protocol error
#dbmi: Invalid procedure 107
#ERROR: Fehler beim Ausführen von: 'UPDATE vectormap SET joinkey="a_value

What causes this error and what could I do to prevent it?

3

On 06/08/13 12:24, Timmie wrote:

How can I perform the corresponding command on the command for the GRASS
table?

In
http://grass.osgeo.org/grass65/manuals/sql.html I found:
v.db.update vectormap column=column3 qcolumn="column1 || column2"

running the command on my data yields:

#dbmi: Protocol error
#dbmi: Invalid procedure 107
#ERROR: Fehler beim Ausführen von: 'UPDATE vectormap SET joinkey="a_value

What causes this error and what could I do to prevent it?

Which database backed are you using (dbf, sqlite, postgresql) ? The manual does state that this command "does not work for DBF driver".

Moritz