Question

The constraint that all foreign keys must either have null values or the value of a primary key in another table is referred to as which of the following?

A. referential integrity rule
B. entity integrity rule
C. foreign key value rule
D. null value rule

Answer 1

A. referential integrity rule

The constraint that all foreign keys must have null values or match a value in another table's primary key column is referred to as the referential integrity rule.

Step-by-step explanation:

The constraint that all foreign keys must either have null values or the value of a primary key in another table is referred to as the referential integrity rule. This rule ensures that the relationships between tables in a database are maintained.

For example, if a table has a foreign key that references a primary key in another table, the value in the foreign key column must either be null or match a value in the referenced table's primary key column.

The constraint that all foreign keys must either have null values or the value of a primary key in another table is referred to as the referential integrity rule.

This rule is a key concept in relational databases, ensuring that relationships between tables remain consistent. It means that any foreign key field must correctly reference a corresponding primary key in the related table or be null if the relationship is optional.