Entity integrity ensures which of the following?

Entity integrity ensures which of the following?

• A. What kind of data can be stored in the field
• B. Null value
• C. Primary key can't contain null
• D. Ensures each record will have its own identity

Answer: (C)

Entity integrity is about ensuring each row can be uniquely identified by its primary key. The essential rule is that the primary key cannot contain null values. If a primary key could be null, a row would lack a definite identity and couldn’t be reliably retrieved or linked to other data. Therefore, the statement that the primary key cannot contain null directly encodes this constraint. While it’s true that this non-null key also helps each record have its own identity as a consequence, the precise, defining rule is the not-null primary key.

Entity integrity is about ensuring each row can be uniquely identified by its primary key. The essential rule is that the primary key cannot contain null values. If a primary key could be null, a row would lack a definite identity and couldn’t be reliably retrieved or linked to other data. Therefore, the statement that the primary key cannot contain null directly encodes this constraint. While it’s true that this non-null key also helps each record have its own identity as a consequence, the precise, defining rule is the not-null primary key.