Core Concept Mastery • DBMS Module
Let's talk about winning an election.
Super Key: This is a big group. For example, {Aadhar Card, Pan Card, Phone Number}. Can these three together identify you? Yes. But is it necessary? Why carry all cards?
Candidate Key: This is the "Minimal Super Key". Just {Aadhar Card} is enough to identify you. or just {Pan Card} is enough. These are "perfect" keys with no extra baggage.
Primary Key: From the candidate keys, we select ONE to be the "Leader". {Aadhar, Pan} are both candidates, but we choose Aadhar as the Primary Key.
Efficiency! We want to identify records using the least amount of data possible. Why use "ID + Phone + Shoe Size" when just "ID" works?
If "ID" is unique, then {ID, Name, Email} is a Super Key (it works, but "Name" is extra). {ID} is the Candidate Key (it's perfect and minimal).
Start: A 'Super Key' can be large {ID, Name, Email}. It works, but it's overkill.
"A minimal super key is known as?"
Candidate Key.