Обсуждение: ECPG and dynamic SQL

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ECPG and dynamic SQL

От
Cliff Wells
Дата:
I'm porting an application from a proprietary database format to
PostgreSQL using ECPG.  My problem is that the application uses a single
function to get a record from the database.  Based upon which table is
being accessed, it dynamically calculates column sizes and returns the
record in a structure.  Creating the query itself is fairly
straightforward, but I am unable to figure out how to retrieve the
_results_ of the query as I have no place to store them (since I don't
know what they will be until the function is called I can't use a EXEC
SQL DECLARE section).

It seems Oracle's sqlda would be a possible solution, but I understand
that isn't implemented in PostgreSQL.
What is the best way to store the results of a dynamic query without
knowing what the results will be beforehand (using ECPG, if possible)?  

I'm using PostgreSQL 7.2.1 on SCO OpenSwerver.

-- 
Cliff Wells, Software Engineer
Logiplex Corporation (www.logiplex.net)
(503) 978-6726 x308  (800) 735-0555 x308



Re: ECPG and dynamic SQL

От
Jim Parker
Дата:
The app GtkSQL does what you need, but it is implimented in libpq.  It will
give you a general idea of how to do it.

Do a google search.

There is another app that is similar (libpq also) a little less complex, so
easier to follow, called dbui-0.4.0  A Google search will give you a URL

cheers
Jim Parker

On 29 Jul 2002, Cliff Wells wrote:
> Date: 29 Jul 2002 15:23:30 -0700
> To: pgsql-interfaces <pgsql-interfaces@postgresql.org>
> From: Cliff Wells <LogiplexSoftware@earthlink.net>
> Sender: pgsql-interfaces-owner@postgresql.org
> Subject: [INTERFACES] ECPG and dynamic SQL
> 
> I'm porting an application from a proprietary database format to
> PostgreSQL using ECPG.  My problem is that the application uses a single
> function to get a record from the database.  Based upon which table is
> being accessed, it dynamically calculates column sizes and returns the
> record in a structure.  Creating the query itself is fairly
> straightforward, but I am unable to figure out how to retrieve the
> _results_ of the query as I have no place to store them (since I don't
> know what they will be until the function is called I can't use a EXEC
> SQL DECLARE section).
> 
> It seems Oracle's sqlda would be a possible solution, but I understand
> that isn't implemented in PostgreSQL.
>  
> What is the best way to store the results of a dynamic query without
> knowing what the results will be beforehand (using ECPG, if possible)?  
> 
> I'm using PostgreSQL 7.2.1 on SCO OpenSwerver.
> 
> -- 
> Cliff Wells, Software Engineer
> Logiplex Corporation (www.logiplex.net)
> (503) 978-6726 x308  (800) 735-0555 x308
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org


Re: ECPG and dynamic SQL

От
Cliff Wells
Дата:
On Mon, 2002-07-29 at 16:37, Jim Parker wrote:
> The app GtkSQL does what you need, but it is implimented in libpq.  It will
> give you a general idea of how to do it.
> 
> Do a google search.
> 
> There is another app that is similar (libpq also) a little less complex, so
> easier to follow, called dbui-0.4.0  A Google search will give you a URL

Yeah, I was afraid there was no way to do it using ecpg... oh well.  

Thanks for the info.


> cheers
> Jim Parker
> 
> On 29 Jul 2002, Cliff Wells wrote:
> > Date: 29 Jul 2002 15:23:30 -0700
> > To: pgsql-interfaces <pgsql-interfaces@postgresql.org>
> > From: Cliff Wells <LogiplexSoftware@earthlink.net>
> > Sender: pgsql-interfaces-owner@postgresql.org
> > Subject: [INTERFACES] ECPG and dynamic SQL
> > 
> > I'm porting an application from a proprietary database format to
> > PostgreSQL using ECPG.  My problem is that the application uses a single
> > function to get a record from the database.  Based upon which table is
> > being accessed, it dynamically calculates column sizes and returns the
> > record in a structure.  Creating the query itself is fairly
> > straightforward, but I am unable to figure out how to retrieve the
> > _results_ of the query as I have no place to store them (since I don't
> > know what they will be until the function is called I can't use a EXEC
> > SQL DECLARE section).
> > 
> > It seems Oracle's sqlda would be a possible solution, but I understand
> > that isn't implemented in PostgreSQL.
> >  
> > What is the best way to store the results of a dynamic query without
> > knowing what the results will be beforehand (using ECPG, if possible)?  
> > 
> > I'm using PostgreSQL 7.2.1 on SCO OpenSwerver.
> > 
> > -- 
> > Cliff Wells, Software Engineer
> > Logiplex Corporation (www.logiplex.net)
> > (503) 978-6726 x308  (800) 735-0555 x308
> > 
> > 
> > ---------------------------(end of broadcast)---------------------------
> > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
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-- 
Cliff Wells, Software Engineer
Logiplex Corporation (www.logiplex.net)
(503) 978-6726 x308  (800) 735-0555 x308



Re: ECPG and dynamic SQL

От
Christof Petig
Дата:
Cliff Wells schrieb:
> On Mon, 2002-07-29 at 16:37, Jim Parker wrote:
> 
>>The app GtkSQL does what you need, but it is implimented in libpq.  It will
>>give you a general idea of how to do it.
>>
>>Do a google search.
>>
>>There is another app that is similar (libpq also) a little less complex, so
>>easier to follow, called dbui-0.4.0  A Google search will give you a URL
> 
> 
> Yeah, I was afraid there was no way to do it using ecpg... oh well.  
> 
> Thanks for the info.

Of course there is a way to do it in ecpg! Ecpg simply does not provide 
the (IMO) overloaded sqlda interface but uses the new lean get 
descriptor interface (SQL standard). See interfaces/ecpg/tests/dyntest* 
for an example.
    Christof

PS: If you want to use this: you can even fetch into a char **results=0; 
but have to free the array afterwards.



Re: ECPG and dynamic SQL

От
Cliff Wells
Дата:
On Mon, 2002-08-05 at 08:45, Christof Petig wrote:
> Cliff Wells schrieb:
> > On Mon, 2002-07-29 at 16:37, Jim Parker wrote:
> > 
> >>The app GtkSQL does what you need, but it is implimented in libpq.  It will
> >>give you a general idea of how to do it.
> >>
> >>Do a google search.
> >>
> >>There is another app that is similar (libpq also) a little less complex, so
> >>easier to follow, called dbui-0.4.0  A Google search will give you a URL
> > 
> > 
> > Yeah, I was afraid there was no way to do it using ecpg... oh well.  
> > 
> > Thanks for the info.
> 
> Of course there is a way to do it in ecpg! Ecpg simply does not provide 
> the (IMO) overloaded sqlda interface but uses the new lean get 
> descriptor interface (SQL standard). See interfaces/ecpg/tests/dyntest* 
> for an example.
> 
>      Christof
> 
> PS: If you want to use this: you can even fetch into a char **results=0; 
> but have to free the array afterwards.
> 

Ah.  Thank you very much!  I don't know how I missed that.  It seems the
quickest way to have someone tell you how to do something is to suggest
it can't be done ;)

Regards,

-- 
Cliff Wells, Software Engineer
Logiplex Corporation (www.logiplex.net)
(503) 978-6726 x308  (800) 735-0555 x308