use Mojolicious::Lite;
use DBI qw(:sql_types);

# ...

get '/eingabe' => sub {
   my $self = shift;
   $self->render( 'eingabe' );
};

get '/insert_database' => sub {
   my $self = shift;
   my $vorname = $self->param('vorname');
   my $nachname = $self->param('nachname');
   my $steuernummer = $self->param('steuernummer');
   my $ort = $self->param('ort');
   my $sth = $dbh->prepare( "INSERT INTO $table 
   ( vorname, nachname, steuernummer, ort ) VALUES ( ?, ?, ?, ? )" );
   $sth->execute( $vorname, $nachname, $steuernummer, $ort );
   $self->render( 'insert_database' );
};

app->start;


__DATA__

@@ eingabe.html.ep
% title 'eingabe';
% layout 'green';
<br /><br />
<form action="insert_database">
   <table>
      <tr><td>Vorname:</td><td><input type="text" name="vorname" /></td></tr>
      <tr><td>Nachname:</td><td><input type="text" name="nachname" /></td></tr>
      <tr><td>Steuernummer:</td><td><input type="text" name="steuernummer" /></td></tr>
      <tr><td>Ort:</td><td><input type="text" name="ort" /></td></tr>
   </table>
   <br /><input type="submit" value="OK"/>
</form>

@@ insert_database.html.ep
% title 'insert_database';
% layout 'green';
<br /><br />
<a href='index'>weiter</a>

<!-- ... -->