Choose the correct answer
Which of the following will be besta
primary key is a database of employee
lan office
Answers
Answer:
o In the EMPLOYEE table, ID can be primary key since it is unique for each employee.
In the EMPLOYEE table, we can even select License_Number and Passport_Number
as primary key since they are also unique.
o For each entity, selection of the primary key is based on requirement and developers.
2. Candidate key
o A candidate key is an attribute or set of an attribute which can uniquely identify a
tuple.
o The remaining attributes except for primary key are considered as a candidate key.
The candidate keys are as strong as the primary key.
For example: In the EMPLOYEE table, id is best suited for the primary key. Rest of the
attributes like SSN, Passport_Number, and License_Number, etc. are considered as a
candidate key.
3. Super Key
Super key is a set of an attribute which can uniquely identify a tuple. Super key is a superset
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