[GRASSLIST:10299] Re: joining attribute tables using SQL commands

[wqual]

Hi Jessi,
it would be helpful, if you could paste the commands and error-messages in 
your posts (what exactly did you try to do with ogr2ogr/ogrinfo?).  And: yes, 
SQL-support of dbf is quite limited [1].

> Hello.
> thanks for the help. what about using ogr2ogr, or ogrinfo? i have both of
> these running on my computer, but was also getting SQL parser errors when i
> tried pretty simple SQL commands. is it just an extremely simplified
> version of SQL?
> i can also try using sqlite----i tried that earlier looking at that
> previous post, but i'll give it another try. i'll still have .dbf files at
> the end if i manipulate them with the sqlite driver, right?
No, because you'll have to switch to another database using db.connect. This 
link [2] might be helpful for you.

> thanks again,
> jessi

Best regards,

Wolfgang

[1] http://grass.itc.it/grass61/manuals/html61_user/dbf.html
[2] http://grass.itc.it/grass61/manuals/html61_user/db.connect.html
>
> >Hi Jessi,
> >unfortunately, it is not possible to join tables with the dbf-driver.
> >However,
> >if you use sqlite, Postgres or Mysql it's possible. There is an example
> > for sqlite on this list:
> >
> >-->
> >http://article.gmane.org/gmane.comp.gis.grass.user/10882/match=sqlite+join
> >
> >Best regards,
> >
> >Wolfgang
> >
> >--
> >
> >Am Montag 13 Februar 2006 pH:11:21 nachmittags/abends schrieb j b:
> > > hello.
> > > I am a beginner trying to join attribute tables.
> > >
> > > To be more specific, I have a .dbf table called streetcl, which gives
> > > street blocks and their various attributes. It contains an attribute
> >
> >called
> >
> > > FNODE_, which is the ID of its starting intersection. I used the
> >
> >command:
> > > echo "ALTER TABLE streetcl ADD COLUMN ELEVFROM double" | db.execute
> > >
> > > to create an attribute called ELEVFROM. In this column, i want to put
> >
> >the
> >
> > > elevation of the intersection where each block originates. I have
> >
> >another
> >
> > > .dbf table called intersect which gives the city's intersections; it
> > > has
> >
> >a
> >
> > > column called ELEV (the intersection's elevation) and a column called
> > > STREETCL_ (the ID of the
> > > intersection as referred to in the streetcl table.)
> > >
> > > This seems like it should not be so complicated, but i'm getting SQL
> >
> >parser
> >
> > > errors.
> > >
> > > My first attempt was this command:
> > >
> > > echo "UPDATE streetcl SET ELEVFROM=(SELECT ELEV FROM intersect WHERE
> > > intersect.STREETCL_=streetcl.FNODE_)" | db.execute
> > >
> > > This tells me:
> > > DBMI-DBF driver error:
> > > SQL parser error in statement:
> > > ...
> > >
> > > Then, to test, I tried to do more simple commands. I created a column
> > > in streetcl called TEST, and tried to set it equal to another column
> > > (same type)
> > > in streetcl, called LENGTH.
> > >
> > > echo "UPDATE streetcl SET TEST=LENGTH" | db.execute
> > >
> > > this gives me the same error. A command like:
> > >
> > > echo "UPDATE streetcl SET TEST=30" | db.execute
> > >
> > > is fine, but even:
> > > echo "UPDATE streetcl SET TEST=30+2" | db.execute
> > > (with or w/out parens around "30+2) gives me the same SQL parser error.
> > >
> > > Any idea what is going on? Am i even going about this in the right way?
> > > Should i be using SQL commands or is there another approach entirely?
> > > thanks very much.
> > > jessi