Certified Information Systems Security Professional (CISSP) Practice Exam

Entity integrity is fundamental in database design because it ensures that every tuple, or row, within a relational database table possesses a unique and non-null identifier, typically represented by a primary key. This uniqueness is essential as it prevents duplicate records within the table, which could lead to data inconsistency and ambiguity. By enforcing a non-null constraint, entity integrity guarantees that every record can be distinctly identified. This uniqueness not only supports efficient data retrieval and manipulation but also plays a pivotal role in establishing relationships between different tables through foreign keys, ultimately maintaining the integrity and reliability of the data throughout the database.

The focus is on the concept that a primary key must always contain a valid entry, as null values would render the identification of a record impossible. Thus, the assurance of both uniqueness and non-null characteristics is vital for the structural integrity of a relational database.