问题
My understanding is that Actice Record is based on a object-relational mapping (ORM) pattern described by Martin Fowler in his book Pattern of Enterprise Application Architecture (Addison-Wesley, 2002); which states a one-to-one mapping relationship exists between a database record and the object that represents it in an object-oriented program (OOP). When Rails creator David Heinemeier sought to implement an ORM for his Rails framework, he based it on Fowler's pattern.
Here's the problem, does ActiveRecord assign a surrogate primary key to every table using the naming convention "ID", and if so, why? Reason I ask is that it appears it'd make more sense to assign a a surrogate primary key using the naming convention "tablename_ID"; as in fact it appears ActiveRecord does when creating foreign keys. Further, is it possible to override the default config, and assign a surrogate primary key using the naming convention "tablename_ID"; reason being that especially in the case of primary keys, it appears to be a good idea not to use a shared name, since telling the difference between two columns ID's is not possible if simply looking at the column namesing: ID, ID, ID. As a use case example of where this appears there would be a problem, if I export data to a single table from two tables, there will be two columns with the ID name; when I import that document with updates, it would appear that there's no way to map the ID columns by default.
回答1:
It's already obvious to see what the ID is, because it is in a certain table. You don't have table_name.table_name_id but table_name.id. I like the distinction between foreign keys and primary keys this way, but admittedly, it's a matter of opinion.
Unless you have a really good reason to use anything other, you should stick to the convention. That's what conventions are for. ActiveRecord gives you the option to change it, like so:
ActiveRecord::Base.primary_key_prefix_type = :table_name_with_underscore
This sets the way primary keys are generated globally. products.id becomes products.product_id.
来源：https://stackoverflow.com/questions/4422042/does-activerecord-assign-a-key-to-every-table-using-the-naming-convention-id