Can I create a table without a primary key?

I want to create a t开发者_高级运维able without a primar key:

users_models

user_id model_id

I have a users table, but the model_id value is actually going to come from a enumeration that I have in my code.

So I don't need a primary key on this table, can I in my migration tell it so it doesn't create one?

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At your migration change :

 create_table :users, {:id => false, :force => true}