Re: managing connecting/disconnecting with odbc

> I'm trying to figure out the best way to manage odbc database
> connections in my system and I haven't been happy with what I've come up
> with so far.  Below is a generic version of my code.  What I'd like is
> for the other parts of my code to be able to call  db_query(Column)
> bound as a test, but also unbound and able to be backtracked through to
> return multiple answers.  The problem of course is that once you go
> through the disconnect you can't backtrack into the query again for the
> next value.
>
> I'd like to be able to call db_query(C). from the SWI command line, have
> it return a value, then be able to use ';' to find the next result, but
> it seems that I've have to expose the detail of managing the db
> connection to do so.  It seems like I'm looking for the ability to
> register a callback for the db_query predicate that always runs the
> disconnect_db code when we know that we're not going to backtrack
> through it anymore.
>
>
> db_query(Column):-
>    connect_db(C),
>    bare_db_query(C,Column),
>    disconnect_db(C).
>
> bare_db_query(C, Column):-
>    odbc_query(C,'SELECT * from my_table', row(Column)).
>
> connect_db(C) :-
>    odbc_connect('dbname', C, [ user(dbuser), password(dbpassword),
>    open(multiple) ]).
>
> disconnect_db(C) :-
>    odbc_disconnect(C).
>
> Has anyone come up with a better way of dealing with this?