On 24/07/08 16:18, Wesley Roberts wrote:
Hi All,
I posted the question below a couple of months ago regarding the use
of v.db.join. At the time I was using version 6.2.3 and even
installed 6.3 but I got no luck using this tool. Markus and I then
communicated several times and still I was not able to join the
tables.
I am thinking that I need some clarification on the tool use and the
importance of 'cat'. In my scenario I was using the 'cat ' column as
my joining field and given that both vector db's had a cat column
this would not help. I then created two new columns with new and
unrelated names and again the 'cat' issue arose. I guess the trick is
to export your join table and remove the cat column / rename it to
something else. Is this the solution? Also I don't think it is wise
trying to join two vectors db files together, I am pretty sure that
is where I went wrong.
Does anyone have a protocol or method to use when joining a the
tables from two vectors currently residing in the same mapset?
You need to eliminate the cat column in one of the two vector attribute
tables. To do so:
v.db.addcol ... col='NewName int'
v.db.update ... col=NewName val=cat
v.db.connect -o ... key=NewName
v.db.dropcol ... cat
Then you should be able to join the two tables.
Wesley Roberts 06/25/08 3:57 PM >>>
One other thing, surely all grass vectors have a column 'cat' and
even if they were not used in the join the problem would persist.
No, having a column named 'cat' is not necessary.
Moritz
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