5 Questions
How is a super key related to a candidate key in the relational model?
A super key is a set of attributes that can uniquely identify a tuple, but it may contain extra attributes that are not necessary for uniqueness. A candidate key is a minimal super key, meaning it is a super key with no repeated data, and it is used to uniquely identify a record.
What are the key characteristics of a candidate key in the relational model?
The key characteristics of a candidate key are: it is a minimal set of attributes that can uniquely identify a record, it must contain unique values, it can contain NULL values, and the value of the candidate key is unique and may be null for a tuple.
Explain what a candidate key is in the relational model and provide an example from the given text.
A candidate key is the minimal set of attributes that can uniquely identify a tuple. It must contain unique values and can contain NULL values. An example from the given text is STUD_NO in the STUDENT relation.
Why is it important for every table to have at least a single candidate key in the relational model?
It is important for every table to have at least a single candidate key because it is used to uniquely identify tuples(rows) in the table, and it is a fundamental requirement of the relational database model.
Can a table have multiple candidate keys? Explain.
Yes, a table can have multiple candidate keys. However, it can only have one primary key. The primary key is selected from the candidate keys to uniquely identify tuples in the table.
Test your knowledge of the different types of keys in the relational model with this quiz. From candidate and super keys to primary, alternate, and foreign keys, this quiz will help you understand the essential concepts of database design and management.
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