Question

Consider the following statements.

A. An entity integrity constraint states that no primary keyvalue can be null.

B. A referential integrity constraint is specified between tworelations.

C. A foreign key cannot be used to refer to its ownrelation.

Identify which of the above statements is/are correct.

? Only A

? Only B

? Only B and C

? Only A and B

Answer 1

Explanation: only A and B

Entity integrity ensures that the primary key value of the table should be unique and cannot be null.And there will be only one primary key in the table.

Refrential integrity specifies the relation between two tables. The refrential integrity can be achieved by the foreign key of one table refers to the primary key of another table.