----- Original Message -----
From: "Tim Bunce" <[EMAIL PROTECTED]>
To: "Dean Arnold" <[EMAIL PROTECTED]>
Cc: "Tim Bunce" <[EMAIL PROTECTED]>; "DBI developers" <[EMAIL PROTECTED]>
Sent: Thursday, April 29, 2004 1:49 AM
Subject: Re: Any interest in a $sth->{TYPE_STRING} ?
> On Wed, Apr 28, 2004 at 11:17:30PM -0700, Dean Arnold wrote:
> >
> > I found an ISO SQL spec (for SQL-99 anyway...
> > has DBI declared any conformance level at this point ?)
>
> No. Though basically it tried to track the latest standards.
>
> > And my interpretations of type string formats seem pretty
> > conformant. However, the "exotics", e.g. ROW, GUID, UDT,
> > etc. will likely have only generic defaults for obvious reasons
> > (questions? just read the spec), but INTERVAL defaults
> > will behave pretty much as I described.
> >
> > Quick poll: how many drivers supply a PRECISION value for
> > INTEGER, REAL, FLOAT, DOUBLE PRECISION ? The std.
> > indicates they can have precision...
>
> How many drivers provide _accurate_ PRECISION for all those types?
>
> And how many databases accept having a PRECISION specified for those types?
>
> And for FLOAT types is PRECISION in the same units as the FLOAT(n)
> parameter? (For float types some databases specify PRECISION in
> decimal digits and some in binary digits, and some change between
> versions :)
>
> Originally you said "either for display purposes, or to generate
> additional queries". Display purposes is fine, you can do anything
> 'reasonable' but "generate additional queries" is a far more demanding
> requirement. It's important to specify *exactly* what the goal is.
>
> And what about modifiers like UNSIGNED, or even AUTO_UNIQUE_VALUE.
>
> Tim.
Actually I would hope that *both* display and query generation would be
possible; in fact, the former should be satisfied by the latter.
My question/efforts are related to default implementation to support
drivers which don't implement a driver specific version.
So should a default implemenation even be provided if it can't
safely meet the 2nd requirement (query generation) ? I'm not certain
DBI specifies enough metadata to completely generate defaults
that can be safely used in query generation (eg, CASESPECIFIC,
CHARACTER SET, in addition to those listed by Tim)
And the exotic types (ROW, UDT, etc) certainly couldn't be fully generated
from the existing metadata.
Dean Arnold
Presicient Corp.
www.presicient.com
