What defines a super key?

What defines a super key?

• A. A minimal set of one or more attributes
• B. Any set of attributes that together uniquely identify an entity instance
• C. Only a primary key
• D. One that combines multiple foreign keys

Answer: (B)

A super key is defined as any set of attributes that together uniquely identify an entity instance within a database. This means that for any given row in a table, the super key will ensure that it can be uniquely distinguished from all other rows based on the values of its attributes. This definition is critical because it highlights the flexibility regarding the number of attributes that can form a super key. A super key can consist of a single attribute or a combination of multiple attributes, as long as they fulfill the uniqueness requirement. In contrast, the other options focus on more specific definitions or incomplete representations. A minimal set of attributes is more characteristic of a "candidate key," which is a type of super key that does not contain any unnecessary attributes. A primary key is a specific, selected candidate key that serves as the main unique identifier for records but does not encompass the broader definition of a super key. Lastly, while foreign keys are involved in establishing relationships between tables, they do not inherently define a super key, which is concerned primarily with unique identification within a single table.

A super key is defined as any set of attributes that together uniquely identify an entity instance within a database. This means that for any given row in a table, the super key will ensure that it can be uniquely distinguished from all other rows based on the values of its attributes.

This definition is critical because it highlights the flexibility regarding the number of attributes that can form a super key. A super key can consist of a single attribute or a combination of multiple attributes, as long as they fulfill the uniqueness requirement.

In contrast, the other options focus on more specific definitions or incomplete representations. A minimal set of attributes is more characteristic of a "candidate key," which is a type of super key that does not contain any unnecessary attributes. A primary key is a specific, selected candidate key that serves as the main unique identifier for records but does not encompass the broader definition of a super key. Lastly, while foreign keys are involved in establishing relationships between tables, they do not inherently define a super key, which is concerned primarily with unique identification within a single table.