Re: DBD::Unify warning codes

On Fri, Jun 05, 2009 at 08:48:44AM +0100, Martin Evans wrote:
> H.Merijn Brand wrote:
> > On Thu, 4 Jun 2009 11:44:51 -0700 (GMT-07:00), Todd Zervas
> > <[email protected]> wrote:
> > 
> >> Do you have any thoughts on how DBD::Unify ought to return warnings?
> >> Specifically I need to be able to detect "dirty reads" (SQLWARN =
> >> -2022).  Is the right DBI way to do this to have DBD::Unify update
> >> SQLSTATE even when there is no error via the h->state method?

The $h->state method isn't meant just for errors.  It should always
return the value of SQLSTATE for drivers that support it.

> > Did you read DBI::DBD? I have no ideas about this one. If it is not
> > documented in DBI::DBD, the best (and only) place to ask is the devel
> > mailing list, which I Cc'd
> 
> Look at DBIh_SET_ERR_CHAR. In a quick glance at DBI::DBD I cannot find
> the relevant information

It's not in a very obvious place (patches welcome):
http://search.cpan.org/~timb/DBI-1.608/lib/DBI/DBD.pm#The_dbd_drv_error_method

> but the following is pulled from DBD::ODBC:
> 
> if (SQL_SUCCEEDED(err_rc)) {
>     DBIh_SET_ERR_CHAR(h, imp_xxh, "", 1, ErrorMsg, sqlstate, Nullch);
> } else {
>     DBIh_SET_ERR_CHAR(h, imp_xxh, Nullch, 1, ErrorMsg, sqlstate, Nullch);
> }
> 
> I believe it is the "" argument. From DBI docs:
> 
> A driver may return 0 from err() to indicate a warning condition after a
> method call. Similarly, a driver may return an empty string to indicate
> a 'success with information' condition. In both these cases the value is
> false but not undef. The errstr() and state() methods may be used to
> retrieve extra information in these cases.

Yeap. Use "" for success with information and "0" for warning
(see also the PrintWarn attribute).

Tim.