sub insert {
  my $self = shift;
  my ($table, $columns, $values) = @_;
  my $sql = sprintf("insert into %s (%s) values (%s)",
                     $table, 
                     join(',', @$columns),
                     join(',' map { '?' } @$values);
  my $sth = $dbh->prepare($sql) or die $dbh->errstr;
  $sth->execute(@$values) or die $sth->errstr;
}

##</code><code>##

  $obj->insert($tablename, \@column_names, \@values)