written 8.5 years ago by | modified 2.9 years ago by |
a | b | C |
---|---|---|
A1 | B1 | C1 |
A1 | B1 | C2 |
A2 | B1 | C1 |
A2 | B1 | C3 |
Database Management System
written 8.5 years ago by | modified 2.9 years ago by |
a | b | C |
---|---|---|
A1 | B1 | C1 |
A1 | B1 | C2 |
A2 | B1 | C1 |
A2 | B1 | C3 |
Database Management System
written 8.5 years ago by |
1. The functional dependencies satisfied by the relation are as follows:
i. A → B
For the tuples t1(A1,B1,C1) and t2(A1,B1,C2), t1 (A) =t2(A)=A1 and t1(B)=t2(B)=B1. Thus, the functional dependency A→B is satisfied by the relation.
ii. C → B
For the tuples t1(A1,B1,C1) and t3(A2,B1,C2), t1 (C) =t3(C) =C1 and t1 (B)=t3(B)=B1. Thus, the functional dependency C→B is satisfied by the relation.
iii. The dependency AC→B can also be obtained.
2. Following are the functional dependencies which are not satisfied.
i. C does not functionally determine A because the tuples t1(A1,B1,C1) and t3(A2,B1,C1) have the same C but different A values.
ii. The same tuples also show B does not functionally determine A.
iii. A does not functionally determine C because the first two tuples t1(A1,B1,C1) and t2(A1,B1,C2)have the same A value and different C values.
iv. The same tuples also show B does not functionally determine C.