Why do I need to use foreign key if I can use WHERE?

Question

A beginners\' question about foreign key in MySQL.

In w3school it says,

A FOREIGN KEY in one table points to a PRIMARY KEY in another table.<

Answer 1

I have another good reason to add the key relationships to your database. There are various code generators that use this information to generate an object model from your database. One notable pattern in common use is the ActiveRecord pattern. Without key relationships, the ActiveRecord pattern would not know how your database entities are related so it would generate a much less useful object model.

Code generation is not appropriate for every software project. But, it is helpful on a large number of projects. If you aren't using code generation you owe it to yourself to at least look into it.