easy5 pts · first answer countssqldata-modelling

What a foreign key enforces

You add FOREIGN KEY (user_id) REFERENCES users(id) to the orders table. What does this constraint guarantee?

A.An order cannot point to a user id that does not exist in usersB.Lookups on orders.user_id become fast because an index is always createdC.Each user can have only one orderD.The user row is copied into each order row

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