use strict;
use warnings;

our $n ||= 10;

# -----------
my @qm = ();
push @qm, '?' while $n--;
my $str = q{CALL DB_PROC_FOO(} . join(q{,}, @qm) . q{)};
# -----------

print $str;

__END__
$ perl -swl qm.pl -n=1
CALL DB_PROC_FOO(?)
$ perl -swl qm.pl -n=2
CALL DB_PROC_FOO(?,?)
$ perl -swl qm.pl -n=3
CALL DB_PROC_FOO(?,?,?)