[Gambas-devel] More Database Driver Changes

[Benoit Minisini]

On Wednesday 19 May 2004 13:08, Nigel Gerrard wrote:
> Benoit,
>
> > Sorry, but I really don't understand what you did about this "multitable
> > fields" thing and it is really necessary.
> >
> > I thought that the old db component was already able to access these
>
> fields by
>
> > using rData["Table.Field"].
> >
> > What's the point exactly ?
>
> Does this work in the current driver ( I have upgraded my postgresql to
> 7.4.1 and there are
> some changes that are needed to the driver to make things work...see my
> changelog...so I
> can no longer test the standard implementation)
> ...

Hi, Nigel!

I finally understood the problem :-)

Let's suppose we have a table named "Table" with two fields "id" and "name".

If we make the following request: "SELECT * FROM Table AS a, Table AS b", we 
get a result object with 4 fields named "id", "name", and yet "id" and 
"name". We do not have the needed unicity of names. This is the problem you 
pointed.

If your solution works, I find it a bit non-optimized. For example, you must 
not do heavy things in field_index(), like getting the postgresql version, of 
checking if we have many different tables in mysql.

And if you do "SELECT * FROM Table AS a, Table AS b", what the different 
database libraries tells you: that all fields come from the table "Table", or 
that some comes from "a" and others from "b". I hope the second case occurs, 
otherwise...

Could you try to optimize what I talked about ? It would be cool :-) If this 
needs slightly modifying the driver interface, tell me. It should not be a 
problem.

You added a optional Type parameter to Table.Create and used an hack for that. 
Modifying the driver interface is needed there. And did you add a equivalent 
property to get the table type too ?

I find Table$Field == Table.Field really being unnecessary. As rData!FieldName 
and rData["FieldName"] compile to exactly the same code, the user could 
always use rData["Table.Field"] if needed. And the '$' character inside an 
indentifier may become forbidden in the future!

You included "../CResult.h" in all drivers. This is a bad idea. We must modify 
the driver interface if you need something from CResult.h. Please explain me 
exactly what you need!

I hope you are not overcame with my remarks :-)

After all previous things corrected, I think we could start thinking about a 
better db component interface. And I you have really a lot of time, talking 
about an ODBC driver :-)

Regards,

-- 
Benoit Minisini
mailto:gambas at ...1...