Computer Science / Unit 8 CS 0421 short lesson, about 20 seconds
Keys: Super, Candidate, Primary
Captions available
The idea
Attributes combining to uniquely identify tuples form superkeys; minimal superkeys are candidate keys; one candidate is selected as the primary key — the unique identifier for each record.
In practice
A vehicle table offers two candidates — identification number, or plate with state — and crowns one.
Where people slip
Minimal means no spare attributes riding along.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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