Hi Stone,
Thanks for your suggestion! I am definitely planning to write this plugin. Could you give me a few more tips as I have no idea how to do it...
I hope answering these questions does not take you more time then writing the plugin yourself...
Are you sure this works? I thought this would translate in 'field_name = NULL' . I thought the correct SQL would be 'field_name IS NULL'. I use
http://www.bookings.org
Thanks for your suggestion! I am definitely planning to write this plugin. Could you give me a few more tips as I have no idea how to do it...

- Should it be a PRE-search_results plugin?
- Can I modify the state in a way that it checks whether a specific column is NULL or NOT NULL? Or should I do all calculations myself and call GT::Plugins->action ( STOP )?
- If I can change the state in some way, which variables do I have to change?
- If I would do the search myself, should I copy all code in Dbsql::Home::search_results(), SQL::Table::_query() and SQL::Base::build_query_cond() and make some modifications in SQL::Base::build_query_cond()? Seems like a lot of work for a small change.
I hope answering these questions does not take you more time then writing the plugin yourself...

Are you sure this works? I thought this would translate in 'field_name = NULL' . I thought the correct SQL would be 'field_name IS NULL'. I use
Code:
GT::SQL::Condition->new('field_name', 'IS', \'NULL' )http://www.bookings.org