olemus
olem muude olemite linkimiseks
= an entity used to link other entities

ülevaateid
https://en.wikipedia.org/wiki/Associative_entity
https://docs.infor.com/ln/10.5.1/fr-fr/lnolh/help/tg/onlinemanual/em000860.html
https://medium.com/@BryanFajardo/how-to-use-associative-entities-in-relational-databases-4456a2c71cda