Re: Can a procedure contain only a SELECT statement?
Date: Thu, 25 Mar 2010 15:10:07 +0000 (UTC)
Message-ID: <pan.2010.03.25.15.10.07_at_email.here.invalid>
On Thu, 25 Mar 2010 13:01:58 +0000, Jonathan Lewis wrote:
> Would anyone care to make a technical comment on my earlier comment
>
> I'm still interested to hear how the front-end code can handle the
> output from a procedure when it doesn't have any information about what
> that output might look like.
Well, there must be some information. If the output type is a cursor, one can describe the cursor. In Perl, which is my front end of choice, a statement handle has the following properties which describe the output rather well: NUM_OF_FIELDS,NAME,TYPE,PRECISION and SCALE. I can always construct my output of choice, based on the handle description, even if I don't know what the original statement looks like, which is frequently the case with the dynamic SQL. However, I have to know that the output type is a cursor, not a scalar variable. So, if my output is a statement handle called $sth, I would do the following:
my $nf = $sth->{NUM_OF_FIELDS};
for ( my $i = 0; $i < $nf; $i++ ) {
my $name = $sth->{NAME}[$i];
my $type = $sth->{TYPE}[$i];
my $prec = $sth->{PRECISION}[$i];
my $scle = $sth->{SCALE}[$i];
my $tn=$db->type_info($type)->{TYPE_NAME}; print
"Field number $i: name $name of type $tn".
"with precision $prec,$scle\n";
}
That would give me the exact description of the output. One cannot know nothing of the output, that would make any programming impossible. Executing a procedure which you know nothing about is like the Russian roulette: you never know when the chamber will be loaded and what will come out of the barrel.
-- http://mgogala.byethost5.comReceived on Thu Mar 25 2010 - 10:10:07 CDT