Choose the correct statement regarding superkeysa)A superkey is an att...
A superkey is an attribute or a set of multiple attributes that can uniquely identify a tuple. It is used to differentiate between tuples.
Choose the correct statement regarding superkeysa)A superkey is an att...
Superkeys in Database Management Systems
Definition of Superkey:
A superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple in a relation or table within a database.
Explanation of the Correct Statement:
The correct statement is option 'A': A superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple.
Understanding Superkeys:
To understand the concept of superkeys, it is important to have a basic understanding of database tables and tuples. In a relational database, a table consists of rows and columns. Each row in a table is known as a tuple, and each tuple has a unique identifier called a key.
A superkey is a set of attributes that can be used to uniquely identify a tuple within a table. It can be a single attribute or a combination of multiple attributes. The key characteristic of a superkey is that it must be able to uniquely identify each tuple in the table.
Example:
Let's consider a table called "Employees" with the following attributes:
- Employee_ID (Primary Key)
- First_Name
- Last_Name
- Email
In this example, the Employee_ID attribute alone can be considered a superkey because it uniquely identifies each employee in the table. Additionally, a combination of attributes like Employee_ID and Email can also be a superkey, as this combination can uniquely identify each employee in the table.
Comparison with Other Statements:
- Option 'B': A superkey is a tuple or a set of multiple tuples that can uniquely identify an attribute. This statement is incorrect because a superkey identifies tuples, not attributes.
- Option 'C': Every superkey is a candidate key. This statement is incorrect because a superkey may or may not be a candidate key. A candidate key is a minimal superkey, meaning it cannot be further reduced without losing the uniqueness property.
- Option 'D': A superkey is an attribute or a set of attributes that distinguish the relation from other relations. This statement is incorrect because a superkey identifies tuples within a relation, not the relation itself.
Conclusion:
In conclusion, a superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple within a relation. It is an important concept in database management systems for ensuring data integrity and efficient data retrieval.
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