I didn't really know how to name the topic. That's probably also the reason why I haven't found answer, so if that was already answerd, sorry for another post.
My point is. I would like to create page field (like author in news or place in calendar) but as a drop down list. But the elements of the list should be taken from table and this table should be avaliable to back-end user.
I need to let article editor to choose place where ceratin event is happening from avaliable locations. He also should be able to add or delete those locations in easy way (best solution would be table just like users, editable from cms).
You could try a HasOneDataObjectManager http://doc.silverstripe.org/modules:dataobjectmanager#relation_dataobjectmanagers or use HasOneComplexTableField out of the box, I think you would have to define Location as a data object type with a has many relation to your pagetype first and define your pagetype as having a has one relation to Location.
More on that: http://doc.silverstripe.org/tutorial:5-dataobject-relationship-management