I don’t know whether my idea below is applicable:
I have 2 tables, namely A and B.
Each row in table A can be associated with zero or more rows of table B.
Each row in table B can also be associated with zero or more rows of table A.
Table A contains (among others) 2 columns AId (as a primary key) and BId (as a foreign key).
Table B also contains (among others) 2 columns BId (as a primary key) and AId (as a foreign key).
A cascade delete rule is also setup for each foreign key relationship in DB and model class.
It means deleting a row of A will also delete rows, associated with it, of B or deleting a row of B will delete rows, associated with it, of A.
Is it practically possible to do this scenario?
I’m assuming that by ‘any-any’ relationship you are referring to ‘many-to-many’.
What you describe in your post is not a many-to-many relation. What you describe is two separate one-to-many relations.
You have a one-to-many relation from TableA to TableB via the AId column in TableB. And you have another one-to-many relation from TableB to TableA via the BId column in TableA. Having two one-to-many relationships in opposite direction is not the same thing as having a many-to-many relationship. Take Stefan’s tagging example and consider three queries (QId1, QId2 and QId3) and three tags (TId1, TId2 and TId3). Try to express that all QId1, QId2 and QId3 are tagged each with all TId1, TId2 and TId3. You’ll realize that you cannot, because you’re trying to express 9 relations in only 6 available ‘foreign key’ fields. A true many-to-many relation requires up to MxN ‘links’ possible between two tables of size M and N, while your design allows for M+N (not surprising, since your design is M links in one of the 1-to-many relations and another N links in the other 1-to-many relation).