How to populate a join table in SQL?

Question

MySQL

There is such a database structure:
I work in MySQL Command Line Client, i.e. I write everything in plain SQL!
Question: how is the link table filled? Do I have to fill it in manually by specifying the org_id and linking it to the service ID (service_id)? Or if you make links between tables, then these fields will be filled in by themselves, and I will only have to set the cost? I just do not know the principle of how this is done, who knows, please tell me.

Answer 1

manually, specifying identifiers from other tables. foreign key will simply prevent you from creating an entry with a non-existent external id