package Customer::EmployeeDB;
use DBI;


my $instance = undef;

sub new { 
    if($instance) {
       return $instance;
    } else { 
        bless { dbh=> undef } ,"Customer::EmployeeDB";
        $self->{dbh}=DBI->connect ("DBI:mysql:database=employee","user","secret")
                or die $DBI->errstr;
        $instance=$self;
        return $self;
   }

}

sub prepare {
   my ($self,$shift)=@_;

   my $sth=$self->{dbi}->prepare($sql) 
         or die $self->{dbi}->errstr;
   return $sth;

}
1;

##</code><code>##

  | handwaving here
use Customer::EmployeeDB;

my $db = new Customer::EmployeeDB();

my $sth = $db->prepare("select * from employee order by surname");
$sth->execute();
   | do something with it