$dbh1 = DBI->connect($DSN,$sqluser,$sqlpass)
    || die "Cannot connect: $DBI::errstr\n" unless $dbh1;
$dbh2 = DBI->connect($DSN2,$sqluser2,$sqlpass2)
    || die "Cannot connect: $DBI::errstr\n" unless $dbh2;


##</code><code>##

sub my_query {
  my $my_dbh = shift;
  my $query = shift;

 ....
}

my_query($dbh1, "select * from potatoes");