Hi,
while fixing the missing OFTDate, I have also activated
the previously commented support for NULL for OFTInteger and
OFTReal types.
Example with DBF driver:
v.db.select natpol col=FLAECHEID,NEW_DATE,VISIBLE
FLAECHEID|NEW_DATE|VISIBLE
0|2005/10/18,F
v.db.update natpol col=FLAECHEID value=NULL
v.db.select natpol col=FLAECHEID,NEW_DATE,VISIBLE
FLAECHEID|NEW_DATE|VISIBLE
|2005/10/18,F
Markus