#!/usr/bin/perl
use strict;
use warnings;

{
    package MyDBI;
    use base qw(DBI);

    package MyDBI::db;
    use base qw(DBI::db);

    sub selectrow_array {
        my ($this) = shift;
        # only for ilustration 
        return $this->SUPER::selectrow_array(@_);
    }

    package MyDBI::st;
    use base qw(DBI::st);
}

my $db = ...;      # any connection, user, pwd
my $user = ...;
my $auth = ...;

my $dbh = DBI->connect(
    "dbi:mysql:$db",
    $user, $auth,
    {   'RaiseError' => 1,
        'RootClass'  => 'MyDBI',
        'PrintError' => 0,
    }
);

warn ref($dbh);
warn join ';', $dbh->selectrow_array("SELECT 'dog', 'cat', 'rat' ");
warn join ';', $dbh->selectrow_array("SELECT 'dog', 'cat', 'rat' FROM no_such_table");