Question

Suppose a relation R(A,B,C) with three numeric attributes. There is a tuple-based constraint, where C is equal to A+B. Which of the followings doesn't violate this constraint?

Select one:
a. None of the others
b. Delete an existing tuple from R
c. Insert new tuple into R
d. Update an existing tuple in R

Answer 1

The action that does not violate the tuple-based constraint C=A+B in a relation R(A,B,C) is deleting an existing tuple from R, as it does not compromise the sum relationship between attributes A, B, and C.

Step-by-step explanation:

The question relates to a tuple-based constraint in a relation R(A,B,C) with attributes wherein C is always equal to the sum of A and B. Given the constraint that C = A + B, the option that does not violate this constraint is:

• b. Delete an existing tuple from R

Deleting a tuple does not affect the integrity of the remaining data with respect to the stated constraint. However, inserting a new tuple without ensuring that C equals A+B, or updating a tuple without maintaining the A+B=C relationship, would violate the constraint. Therefore, the correct action that maintains data integrity in the context of the given constraint is the deletion of a tuple.

In the given relation R(A,B,C), where C is equal to A+B, the tuple-based constraint is that the value of C must always be equal to the sum of A and B. So, any operation that violates this constraint would not be allowed. In the given options, selecting 'a. None of the others' is the correct choice as all the other options would violate the tuple-based constraint.