[Gambas-devel] Gambas & ODBC

[Andrea Bortolan]

 --- Benoit Minisini <gambas at ...1...> ha
scritto: 
> On Wednesday 29 December 2004 12:03, Andrea Bortolan
> wrote:
> >
> > No problem for an iSeries ;-)
> >
> > You're right ! It is horrible ! But this happens
> only
> > if the ODBC driver doesn't return the number of
> rows.
> > This is the iSeries ODBC driver case but not the
> MySQL
> > driver.The MySQL driver returns the rows as we
> expect
> > (but this is not the ODBC standard).
> > The Gambas DB allocates the memory for the results
> > before starting fetching rows so if the rows
> number is
> > not right I can face some problem (no rows
> showed).
> >
> > > But, the problem with ODBC is always there: how
> to
> > > implement all the functions
> > > that return the structure of the database ? I
> know
> > > there are some special
> > > queries in ODBC for that, named "catalog
> functions".
> >
> > The problem with the catalog ecc. is that the
> > Databases behavior is different one from others,
> i.e.
> > in the DB2/400 (iSeries ex AS/400) database you
> cannot
> > create  a new database, you can create a new
> library
> > where put the tables and this is referred as
> > collection using the library.table or
> library/table
> > schema to address them. So the driver cannot
> execute a
> > "create new database" command, the same command
> can
> > instead work i.e. in MySQL.
> 
> So the gb.db component should manage the case when a
> driver function cannot be 
> implemented. At the moment, this is possible by
> raising an error inside 
> driver functions that cannot be implemented.
> 
> We can decide that in the ODBC gambas driver,
> creating and destroying 
> databases are impossible.
> 
> > The ODBC does not provide those functions, the way
> you
> >  can implement those funcion in order to get the
> > database structure is to  query the database
> catalog
> > tables using the SQL but this is a common SQL
> query.
> >
> > > If you want to finish the implementation of the
> ODBC
> > > driver, here is the only
> > > information I have about catalog functions. I
> found
> > > them on the ODBTP site:
> > > http://odbtp.sourceforge.net.
> >
> > I started to use the unixODBC ODBC iplementation
> > because many database drivers are available for
> this
> > driver manager (included the iSeries ODBC driver).
> > unixODBC is written using the Microsoft standard
> > (Microsotf created the ODBC) and I looked at the
> > Microsoft documentation
> >
>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/o
> >dbcodbc_api_reference.asp
> >
> > .
> > I also started to create a new Gambas modules
> "ODBC"
> > that does not leverage on the Gambas DB class, but
> > this seems to duplicate many things and I don't
> know
> > which it the best way in order to have an ODBC
> > connection...plese let me know your thought.
> >
> 
> The big problem is that ODBC seems to be NOT
> database independant, contrary to 
> the gb.db component that relies on its drivers. For
> example, dates in 
> ODBC/SQLServer queries can be different from dates
> in ODBC/MySQL queries. Can 
> you ensure that the same query syntax will work for
> every ODBC driver, at 
> least for the values (dates, numbers and strings) ?
> 
This should be done by the ODBC standard !? The Odbc
API are able to returns dates in many formats but all
those format are standard and unique.

> As for the catalog functions, do you plan to
> implement them as much as 
> possible ? I found another link about them:
> 
>
http://gsbwww.uchicago.edu/computing/research/SASManual/accdb/z0421269.htm
> 
> 
> > I started to code ODBC because I'm an iSeries
> > techincal pre sales and I think that many ISV can
> > start to deveolop their application in Linux if
> they
> > can try Gambas. But all those ISV have OS/400
> > customers and the way to have Linux applications
> that
> > uses the DB2/400 is  having ODBC. When this ODBC
> > modules will be available I  cat start to create
> some
> > seminars and documentation on how use Gambas to
> crate
> > Linux application instead VB.
> 
> Cool :-)
> 
> Best regards,
> 
> -- 
> Benoit Minisini
> mailto:gambas at ...1...
> 
> 
>
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