Question

Suppose a relation R(A,B,C,D) and a constraint says that in every tuple of this relation a value on D component must be equal to the total of values on other components. How can we implement this constraint?

Select one:
a. We create a referential integrity constraint
b. We create a not null constraint
c. We create four attribute-based CHECK constraint for each attribute
d. We create a tuple-based CHECK constraint

Answer 1

To implement the constraint, create a tuple-based CHECK constraint that specifies that the sum of values in A, B, and C must equal the value in D for every tuple in the relation.

Step-by-step explanation:

To implement the constraint that in every tuple of relation R, the value of D must be equal to the total of values on other components, we can create a tuple-based CHECK constraint. This constraint allows us to specify a condition that must be met for each tuple in the relation. In this case, the condition would be that the sum of values in A, B, and C must equal the value in D. By creating this constraint, we ensure that the constraint is enforced for every tuple in the relation.