Question

Statement 1: Referential Integrity refers to the validity of an attribute domain. True or False.

Statement 2: In SQL, when Create a table, the foreign key must be not null. True or False.

a) Both are True

b) 1 is True, 2 is False

c) 1 is False, 2 is True

d) Both are False

Answer 1

Statement 1: Referential Integrity refers to the validity of an attribute domain. False.

Statement 2: In SQL, when Create a table, the foreign key must be not null. False.

d) Both are False

Foreign keys mean the value must exist in the other table. NULL refers to the absence of value, so when you set a column to NULL, it wouldn't make sense to try to enforce constraints on that.

Yes, the value can be NULL.

Referential integrity refers to the relationship between tables. Because each table in a database must have a primary key, this primary key can appear in other tables because of its relationship to data within those tables.

Yes, it can be NULL