For a relational schema R(A, B, C, D, E, F) consider the following Functional…
2026
For a relational schema R(A, B, C, D, E, F) consider the following Functional Dependencies (FDs):
A ➡ B
C ➡ DF
AC ➡ E
D ➡ F
Determine the key from the given Functional Dependencies (FDs).
- A.
ACB
- B.
ACD
- C.
AC
- D.
AB
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Correct answer: C
To find the key, identify attributes not appearing on the right-hand side of any functional dependency. Here, A and C do not appear on the RHS, so they must be part of the key. Calculate the closure of AC: (AC)+ includes A and C. Using A → B, we get {A, B, C}. Using C → DF, we add D and F to get {A, B, C, D, F}. Using AC → E, we add E to get {A, B, C, D, E, F}. Since the closure contains all attributes and neither A nor C alone determines all attributes, AC is the candidate key.