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Re: [vox-tech] Perl question, DBI - Why no selectcol_array method?
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Re: [vox-tech] Perl question, DBI - Why no selectcol_array method?



On Fri, Apr 27, 2001 at 05:34:08PM -0700, jdnewmil@dcn.davis.ca.us wrote:
> On Fri, 27 Apr 2001, Micah Cowan wrote:
> 
> > On Fri, Apr 27, 2001 at 03:28:58PM -0500, Jay Strauss wrote:
> > > In DBI there is:
> > > 
> > >       $ary_ref = $dbh->selectrow_arrayref($statement);
> > >       @row_ary = $dbh->selectrow_array($statement);
> > > 
> > > but only
> > > 
> > >       $ary_ref = $dbh->selectcol_arrayref($statement);
> > > 
> > > Why??? (i.e why no @col_ary = $dbh->selectcol_array($statement))
> > 
> > Dunno.  You'll have to ask the author  :)
> 
> I think this would encourage inefficient programming constructs, because
> such a function would imply a complete iteration through all the rows and
> columns while ignoring all but one.  It is more efficient to use a query
> that only returns the single column you are interested in.

I don't think it would imply that at all.  Whether it returns a list,
or a reference to an array, it still does the same iteration.  If
something can return a reference to a (newly constructed) array, one
could certainly return a list of values just as easy.  Or did I
misunderstand you?

It might be that it was done this way to eliminate a copy of the list
created by this method into the return value, but I really don't know
anything about the DBI (or Perl) internals, so I really can't say.

Micah


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