DB API question - where is a stored procedure's return value?

[random832 at fastmail.us]

On Thu, Mar 13, 2014, at 13:01, Chris Angelico wrote:
> On Fri, Mar 14, 2014 at 1:43 AM, John Gordon <gordon at panix.com> wrote:
> >> select foo() as value from dual
> >
> > That will get the return value into an SQL variable, but the OP wanted
> > to know how to fetch it from python code.
> 
> In theory, that should produce a one-row-one-column SELECT result,
> which can then be retrieved as such. (I say "in theory" because not
> all back-end databases support the "from dual" notation - which, by
> the way, I find extremely odd; what's 'dual' about it?)

DUAL is an Oracle thing. It used to have two rows, in order to be used
to duplicate results by doing a cartesian join to it. At some point,
that was removed, but the name stuck.

Most other servers allow SELECT without FROM.