[GRASS-user] v.patch error: Column types differ

[Moritz Lennert]

On 04/04/12 14:50, RichardC wrote:
> Hi,
>
> I'm trying to join vector layers using v.patch and run into the 'column
> types differ' error.
>
> I can see the difference relating to the data type of a column via the
> attribute table in GRASS. However, is there a way through GRASS that I can
> modify the data type?
>
> I've tried opening the DBF file in openoffice, but after saving the changes
> they seem to be lost on reopening the DBF file. I've also unchecked
> sheet/document protection in openoffice. Have also tried exporting as CSV
> and reimporting and saving as DBF in openoffice.
>
> Would welcome any suggestions on the simplest approach. QGIS also does not
> appear to allow changing of data type through its GUI interface.

The easiest would probably be to create new columns of the desired type 
(with v.db.addcolumn) and to copy the data from the old columns into the 
new columns, for example with v.db.update qcol=.

Moritz