Question 11

Data values in a primary key cannot contain null or blank values.

A primary key must have unique values for each record in a database and cannot contain null or blank values, ensuring that each entry is identifiable and distinct.

A) It cannot contain name values

This statement is incorrect because a primary key can contain name values as long as those values are unique and not null. Name values can serve as identifiers in a primary key, provided they meet the uniqueness requirement.

B) It cannot contain null or blank values

This statement is correct as a primary key must have a unique value for each record and cannot contain null or blank values. The integrity of the primary key is essential for proper database functioning, and null or blank values would violate that integrity.

C) It cannot contain zero values

This statement is incorrect. While zero can be used as a value in a primary key, it must be unique and not null. Thus, zero can be a part of a primary key as long as it does not duplicate other values.

D) It cannot contain number values

This statement is incorrect because a primary key can indeed contain number values. Numeric values can be unique identifiers, and as long as they are not duplicated and are not null, they are valid for use in a primary key.

Conclusion

Option B is definitively correct because it emphasizes the requirement that primary keys must contain unique, non-null values to ensure each record can be distinctly identified. All other options fail to recognize the flexibility of data types used in primary keys or misinterpret the constraints associated with them.