What is Super-Key? Short note on Super Key
Super Key :-
A super key for an entity set is a set of one or more attributes whose combined value uniquely identifies the entities in the entity. For example, an entity CUSTOMAR contains the attributes CUST-NO, CUST-NAME, ADDR . The CUST-NO attribute of the entity set CUSTOMER is sufficient to distinguish one customer entity from another. Therefore, CUST-NO is a super-key. Similarly the combination of CUST-NO and CUST-NAME is a super key for the entity set CUSTOMER. The CUST-NAME attribute is not a super-key, as several people might have the same name.
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