package Exported;

  # all the usual stuff here...

  my $dbh;

  sub set_dbh ( $ )
  {
      ( $dbh ) = @_;
  }

  sub do_query ( $ )
  {
      my ( $key ) = @_;
      return $dbh->selectrow_hashref( ... )
  }

##</code><code>##

  my $dbh = DBI->connect( ... );
  set_dbh( $dbh );
  my $answer = do_query( $key );

##</code><code>##

  package MyQuery;

  sub new
  {
      my ( $class, $dbh ) = @_;
      return bless { dbh => $dbh }, $class;
  }

  sub do_query
  {
      my ( $self, $key ) = @_;
      return $self->{dbh}->selectrow_hashref( ... );
  }

##</code><code>##

  my $dbh = DBI->connect( ... );
  my $query_obj = MyQuery->new( $dbh );
  my $answer = $query_obj->do_query( $key );

##</code><code>##

  package Exported;

  # blah blah blah  :)

  our $dbh;
  *dbh = \$main::dbh;

  # now you can refer to just $dbh and it will use the
  # value in $main::dbh
  sub do_query ( $ )
  {
      my ( $key ) = @_;
      return $dbh->selectrow_hashref( ... );
  }