If X1, X2, X3, ..., XN are the domains in a relational database model, then…
2018
If X1, X2, X3, ..., XN are the domains in a relational database model, then the relation (table) is a subset of which of the following?
- A.
X1 × X2 × X3 × ... × XN
- B.
X1 + X2 + X3 + ... + XN
- C.
X1 U X2 U X3 U ... U XN
- D.
X1 ∩ X2 ∩ X3 ∩ ... ∩ XN
Attempted by 227 students.
Show answer & explanation
Correct answer: A
In relational database theory, a relation is formally defined as a subset of the Cartesian product of its attribute domains. Since X1 through XN represent these domains, the relation is a subset of their Cartesian product (X1 × X2 × ... × XN).