[TYPO3-mvc] RELATION_HAS_ONE and OPERATOR_NOT_EQUAL_TO

[Cornelius Illi]

Hi everyone,

does anybody know a source, where to find something about different 
types of relations N:M, 1:M and especially 1:1?
There is an example for a 1:M in the extension "blog_examples" for 
author's of posts and comments (as announced here: 
http://lists.typo3.org/pipermail/typo3-project-typo3v4mvc/2009-July/000586.html)
However, the Query used an IN-Statement so that a comma-seperated list 
would also be accepted, which would allow a N:M-Relation aswell.
It works, just wanna know the concept behind it.

Also i was in need of using a Comparison with  OPERATOR_NOT_EQUAL_TO as 
an operator. Unfortunately there is not method like $query->nequals(), 
so I used something like this:

  t3lib_div::makeInstance('Tx_Extbase_Persistence_QOM_Comparison',
                                 
t3lib_div::makeInstance('Tx_Extbase_Persistence_QOM_PropertyValue', 
'additionaldata.description', ''),
                                 
Tx_Extbase_Persistence_QueryInterface::OPERATOR_NOT_EQUAL_TO, '');

Any better solution to do so?
@Jochen/ Sebastian: Does your book cover questions like this?

Cheers, Cornelius