sub sth_registration_factory {
  my $self = shift;
  my $sth_name = shift;

  unless( $self->sth->{$sth_name} ){
    my $sql = $self->cfg->param("sql.sql_$sth_name");
    my $self->sth->{$sth_name} = $self->dbh->prepare( $sql );
    print "$sth_name : $sql \n\n" if $self->debug;
  }

  return;
}