constraints require that a corresponding value for a foreign key must exist as a primary key in the related table. For example, an order with a users_id value of 23890 can only be recorded if there’s already a users record with an id of 23890.
- 3. First Site: Structure and Design
- from Effortless E-Commerce with PHP and MySQL, Second Edition
- Publisher: New Riders
- Released: December 2013
foreign key constraints
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