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

[Tim Michelsen]

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