Re: Problem in GNATColl when using prepared queries: GNATCOLL.SQL.POSTGRES.GNADE.POSTGRESQL_ERROR is raised

["Thomas Løcke" <tl@ada-dk.org>]

On 2011-02-25 21:08, Dmitry A. Kazakov wrote:
>>      Cur.Fetch (Connection =>  Connection,
>>                 Stmt       =>  P,
>>                 Params     =>  (1 =>  +Some_Name'Access));
>>
>
> That does not look like an execution of the statement P. I would expect
> fetch rather walking through the result set than executing anything. But I
> don't know GNATColl.


The comment for the Fetch procedure reads:

    --  Execute a prepared statement on the connection.


> Does it that right? I am asking this, because it is an issue in ODBC, where
> the cursor state depends on many factors and that the same sequence of
> calls may either close the cursor or not depending on the operation
> outcome.


I've not experienced any problems with GNATColl and cursors. It just
works.

Except of course in this specific case, where I can't make it work. hehe


>>     while Cur.Has_Row loop
>>        Put_Line ("id="&  Cur.Integer_Value (0)'Img);
>>        Put_Line ("name="&  Cur.Value (1));
>>        Cur.Next;
>>     end loop;
>
> What is the semantics of Has_Row does it refer the current row or that Next
> would not fail when called?


I'm not quite sure I understand what you mean Dmitry. Could you elaborate?



> That means that you are doing something wrong. Bound values must work.


Exactly. And that part does work. I can see in the trace that the query
is correct, and I can see it executed perfectly in the PostgreSQL log.

The problem occurs _after_ the query has been executed. Things go bad
when I try to extract the data, and it only fails when I'm using a
prepared and parameterized query, re. my original post:

    If I get rid of the Cur.Integer_Value (0) and Cur.Value (1) calls
    in the while loop from the prepared example, then I also get rid
    of the exception, so it appears to be some sort of issue with the
    *Value functions and prepared queries.

I'm pretty sure this is a bug somewhere in GNATColl.


-- 
Thomas L�cke

Email: tl at ada-dk.org
Web: http//:ada-dk.org
http://identi.ca/thomaslocke