Question

Which rule states that the user has to conserve the
consistency between the primary and the foreign key, that is,
each primary key have a fitting entry of primary key?
A Referential integrity
B Composite indexes
C Multiple indexes
D None the above​

Answer 1

Answer:

A: Referential integrity

Step-by-step explanation:

Referential integrity requires that a foreign key must have a matching primary key or it must be null. This constraint is specified between two tables (parent and child); it maintains the correspondence between rows in these tables. It means the reference from a row in one table to another table must be valid.

Answer 2

Referential integrity states that the user has to conserve the  consistency between the primary and the foreign key.

• According to this integrity in another direct relationship, a foreign key should be null or should match a primary key value.
• Referential integrity is a data property stating the actual references within it.  
• Any specific column in a base table declared to remain a foreign key must properly contain either a null value or only values from the parent table's primary key or a candidate key.
• This will enable the referential integrity to be properly entered into a relational database.