What does the term "alternate key" refer to in data management?

What does the term "alternate key" refer to in data management?

• A. An identification used as a primary key
• B. A key that is unique but not the primary key
• C. A secondary key used for indexing purposes
• D. A composite key made up of multiple attributes

Answer: (B)

The term "alternate key" refers to a key that is unique but not designated as the primary key in a database table. An alternate key serves as an additional means of identifying records uniquely in a table, providing flexibility in access methods while ensuring data integrity. For example, in a table where a primary key is an employee ID, an alternate key could be the employee's email address, as it is also unique to each employee but not used as the primary means of identification. Using alternate keys allows for efficient indexing and can enhance querying capabilities while maintaining the ability to enforce uniqueness constraints on multiple fields. In this context, other options lack the precise definition of an alternate key. An identification used as a primary key cannot be an alternate key. A secondary key typically refers to any key that is not a primary key and is generally used for referencing, but it does not necessarily imply uniqueness. A composite key refers specifically to a key that comprises multiple attributes, which does not align with the concept of an alternate key being simply a unique designation separate from the primary key.

The term "alternate key" refers to a key that is unique but not designated as the primary key in a database table. An alternate key serves as an additional means of identifying records uniquely in a table, providing flexibility in access methods while ensuring data integrity.

For example, in a table where a primary key is an employee ID, an alternate key could be the employee's email address, as it is also unique to each employee but not used as the primary means of identification. Using alternate keys allows for efficient indexing and can enhance querying capabilities while maintaining the ability to enforce uniqueness constraints on multiple fields.

In this context, other options lack the precise definition of an alternate key. An identification used as a primary key cannot be an alternate key. A secondary key typically refers to any key that is not a primary key and is generally used for referencing, but it does not necessarily imply uniqueness. A composite key refers specifically to a key that comprises multiple attributes, which does not align with the concept of an alternate key being simply a unique designation separate from the primary key.