...
use Data::Dumper;
...
my @ref_header = ( 
	   [ ["Name", "Surname"] ],
    );
...
@ref_db_data = $sth->fetchall_arrayref;

##</code><code>##

print Dumper @ref_db_data;
$VAR2 = [
          [
            'John',
            'Doe'
          ],
          [
            'Jane',
            'Smith'
          ],
        ];