my $query = "select * from my_table";

my $sth = $dbh->prepare($query);

$sth->execute or die "Error: unable to run query! " . $dbh->errstr;

while (my $cols_ref = $sth->fetchrow_arrayref ) {
   print "@$cols_ref\n";
   print "$_ : " foreach @$cols_ref;
   print "\n";
}