DBI202Xuất hiện trong 1 đề thi
Given the relational schema $R(A,B,C,D,E)$ and the set of functional dependencies: $F=\{AB\to C, B\to D, C\to E, D\to B\}$.\nWhat is the closure of the attribute set $\{A,B\}$?
Các lựa chọn
A$\{A,B,C,D\}$
B$\{A,B,C,D,E\}$
C$\{A,B,C,E\}$
D$\{A,B,D\}$