How does Rails migration enforce relationships?

Question

At startup:

rake db:migrate

only files that are in db / migrate / right are processed?

Well, since application / models define relationships such as one-to-one, one-to-many, and many-to-many relationships, how does Rails apply such relationships? After migrating and viewing the generated database schema, I do not see foreign key constraints. So it baffles me how it all works.

Answer 1

Quite simple.

This is due to the need to support multiple databases. Some, like sqlite, do not support foreign keys.

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Answer 2

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Answer 3

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