Which choice best describes a composite primary key?

Which choice best describes a composite primary key?

• A. A single unique identifier used across multiple tables
• B. More than one attribute is used to create a unique identifier
• C. Keys that are dependent on foreign keys
• D. A key that allows random data entry

Answer: (B)

A composite primary key is best described as more than one attribute being used to create a unique identifier for a record within a table. This type of key combines two or more columns in a database table to ensure that each record can be uniquely identified by the combination of values from these columns. This is particularly useful in scenarios where a single attribute is not sufficient to ensure uniqueness, allowing for a more detailed and specific identification of records. For instance, in a table representing student enrollment in courses, both student ID and course ID might be combined to create a composite primary key, as a single student can enroll in multiple courses, and a course could have multiple students. The incorrect options provide different characteristics of keys. A single unique identifier used across multiple tables pertains to a foreign key relationship rather than a composite primary key. Keys that are dependent on foreign keys refer to relationships and dependencies in database design but do not define a composite primary key. A key that allows random data entry does not relate to the concept of a primary key, which is fundamentally about maintaining integrity and uniqueness in the dataset.

A composite primary key is best described as more than one attribute being used to create a unique identifier for a record within a table. This type of key combines two or more columns in a database table to ensure that each record can be uniquely identified by the combination of values from these columns. This is particularly useful in scenarios where a single attribute is not sufficient to ensure uniqueness, allowing for a more detailed and specific identification of records.

For instance, in a table representing student enrollment in courses, both student ID and course ID might be combined to create a composite primary key, as a single student can enroll in multiple courses, and a course could have multiple students.

The incorrect options provide different characteristics of keys. A single unique identifier used across multiple tables pertains to a foreign key relationship rather than a composite primary key. Keys that are dependent on foreign keys refer to relationships and dependencies in database design but do not define a composite primary key. A key that allows random data entry does not relate to the concept of a primary key, which is fundamentally about maintaining integrity and uniqueness in the dataset.