Re: Functions returning sets

On Sat, 19 May 2001, mlw wrote:

> Stephan Szabo wrote:
> > 
> > (Machine couldn't find mx record for mohawksoft, replying only
> > to list)
> > 
> > On Sat, 19 May 2001, mlw wrote:
> > 
> > > Sorry to gripe here. Don't get me wrong, I think Postgres is amazing, and I
> > > think all you guys do an amazing job.
> > >
> > > Is it just me, or do others agree, functions returning sets need to be able to
> > > be used in a select where equal clause.
> > >
> > > select * from table where field = funct_set('bla bla');
> 
> I don't understand your reasoning.  Look at the syntax:
> 
> select * from foo where bar = function(...);
> 
> If function() returns one value, then only one will be returned and the
> relation features of postgres can be used, as in "select * from foo, this where
> foo.bar = function() and foo.bar = this.that"
> 
> If function() can return multiple values, should it not follow that multiple
> values should be selected? 

What does select * from foo where bar=(select value from foo2) mean when
the second returns more than one row.  IIRC, sql says that's an error.
I don't see why functions returning sets would be different than a
subquery.  That's what =ANY, =ALL, and IN are for.  I don't see what the
difference between doing this with =s and making IN work better really is.