Schema design

Primary keys, foreign keys, and shaping tables so a fact is stored exactly once. Interviewers ask this alongside query-writing, not instead of it, and it's the half a query-language tutorial alone never covers.

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easyAdd a primary key to an unkeyed orders tableLazada · schema-designFree→easyClose the loophole on a column that's never actually nullGXBank · schema-designFree→mediumLink orders to customers with an enforced, cascading foreign keyShopee · schema-designFree→