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What is the difference between a primary key and a foreign key?

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01

Understand the problem

Explain keys.

primary-keyforeign-key
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03

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A primary key uniquely identifies each row in a table (unique + not null). A foreign key references a primary key in another table, enforcing referential integrity so you can't reference a non-existent row.

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04

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SQLPrimary Key vs Foreign Key Playground
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