The database I'm currently building is pretty complicated to me. So it would be much more complicate if i try to explain so i will try to generalize. The question is at the end of the post.
So I created a little database model. The Tables are connected with a n:m relationship. Only the manufacturer and the machine tables have a 1:n relationship to machine_manufacturer.
The table PlanForMakeACar holds information about to build a car and has a relationship to the table "measurementData" which holds created data while the production process.
The table "machine_manufacturing" just holds the information for the group "manufactures" which machines do they have for production.
Is that okay or do i miss something to avoid the loop?
My researches showed me the following contribution:
Why sould I avoid loops
Best Answer
Loops are not in themselves a sign of a modelling problem, and I think the other question that you reference demonstrates that quite well.
It may help to think of "context" for joins, which is the concept that the business situations in which different potential joins apply express different business contexts.
For example, a person can be "connected" with a car manufacturer because she owns a car built by them. She might also be connected because she subscribes to an email bulletin from them. She might also be employed by them.
Three different contexts, and while it is conceivable that two contexts might be invoked by a query ("find all Honda owners who are not subscribed to their email bulletins"), the more usual query is going to be within one particular context, and hence not involve "loops" in the query.
I'm not aware that this concept of the "context" is in any way a formal approach to analysis, although I wouldn't rule it out, but it may be helpful to consider it.