DBI202Xuất hiện trong 2 đề thi
Consider the relation $R(A,B,C,D,E,F,G,K)$ and functional dependencies: $A,B \to C$, $B \to C$, $C \to A,D$, $D \to E$, $C,F \to B$, $G \to K$. What is the closure of $\{A,B\}$?
Các lựa chọn
A$\{A,B,C,D,E\}$
B$\{A,B,C,D,E,F\}$
C$\{B,C,D,E\}$
D$\{A,B,C,D\}$
E$\{A,B,C,F,G\}$