[GRASSLIST:1390] Re: problems connecting to database via odbc & v.reclass.pg problems

[mlennert at club.worldonline.be]

> > As to the postgres modules, they are great, but there still seems to be an 
> > inconsisteny in the v.reclass.pg html-page. In the text, sql queries are 
> > mentioned, but in the "synopsis" section the keyword is 'pql'. Then in the 
> > description of the keywords, no mention of pql, but of sql. In the example, 
> > the same problem again:
> > 
> > "v.reclass.pg sql=vect.sql key=tlid input=t.roads.pg out­put=t.roads.12 
> > 
> > vect.pql: retrieve unique (t.tlid,t.cfcc) from t in type1
> > where cfcc ~ "A1"
> > sort by tlid"
> > 
> > So, if someone could explain, what I should use, sql or pql...
> Thanks for identifying the inconsistency. I have updated the html
> page to "sql" and "postQUEL" to "SQL". See here:
> http://www.geog.uni-hannover.de/grass/gdp/html_grass5/database.html
> 
> > Also, I do not find the explanation of the 'where' parameter very clear.
> > How should this be formulated exactly ? And if I understand correctly, I
> > can only extract one set of data if I use this option, i.e. I can only
> > create one category.
> 
> Please remind that the *.pg pages might need final updating (web page:
> "(note: needs to be updated)"). If you encounter other problems or have text
> pieces to improve the pages, please let me know.

Thanks for doing the update, but is the "retrieve" statement you use in the 
example a valid SQL command ? I can't find it in the postgresql commands. 
Should'nt it be "select" ?

Secondly, I think an example for the other way of using v.reclass.pg, i.e. 
without an external sql file would be very helpful.

> > I find the odbc reclass much easier to use, but this might just be my lack of 
> > understanding of v.reclass.pg
> > 
> > More generally, I like the idea of having one interface (odbc) which I can
> > use in several programs, such as Grass, R, etc...
> Yes, that's the intention of Radim's db.* modules...

Yes, and I want to thank him again for those...if only I could get them to work here ;-)

I also read the paper that Roger and you (Markus) wrote on R, Grass, and Postgres and I do believe that this is an important issue, as it touches user friendliness in terms of data handling...

Moritz