{
    my @FIELDS = qw( field1 field2 field3 );

    sub run_insert 
    {
        my $dbh = shift || return;
        my ($field1, $field2, $field3) = @_;

        my $sql = q/
            INSERT 
            ( / . 
                join(',' @FIELDS) . 
            q/)
            INTO some_table 
            VALUES 
            ( *** PLACEHOLDERS HERE ***)
        /;
        my $sth = $dbh->prepare($sql);
        $sth->execute($field1, $field2, $field3);
        $sth->finish;
    }
}

##</code><code>##

$BEGINING_SQL . 
join(',', map('?', @FIELDS)) . 
$ENDING_SQL;

##</code><code>##

$BEGINING_SQL . 
join(',', '?' x @FIELDS) . 
$ENDING_SQL;

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw( cmpthese );

my $count = shift || 100000;
my @test_array = (0 .. 99);

sub map_bench 
{
	my @array = map { '?' } @test_array;
}

sub x_bench 
{
	my @array = '?' x @test_array;
}

cmpthese($count, {
	map => \&map_bench, 
	x   => \&x_bench, 
});


__OUTPUT__
Benchmark: timing 100000 iterations of map, x...
       map: 76 wallclock secs (76.75 usr +  0.00 sys = 76.75 CPU) @ 1302.93/s (n=100000)
         x:  1 wallclock secs ( 1.91 usr +  0.00 sys =  1.91 CPU) @ 52356.02/s (n=100000)
       Rate   map     x
map  1303/s    --  -98%
x   52356/s 3918%    --