The x operator does not work that way. Consider this:

#!/bin/env perl
use strict;
use warnings;
use Data::Dumper;

my @records = ( ['value1', 'value2'], ['value3', 'value4'], ['value5',
+ 'value6']);

my @broken = ('( ?, ? )' x @records);
print 'broken: ', Dumper \@broken;

my @fixed = ('( ?, ? )') x @records;
print 'fixed: ', Dumper \@fixed;
__DATA__
broken: $VAR1 = [
          '( ?, ? )( ?, ? )( ?, ? )'
        ];
fixed: $VAR1 = [
          '( ?, ? )',
          '( ?, ? )',
          '( ?, ? )'
        ];
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This example leads us to the corrected line of your original code:

my $values = join ", ", ("( ?, ? )") x @records;
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