Multiple choice:The five basic relational algebra operations are ().
The five basic relational algebra operations are ()@[ A](2)
A. ∪ - × σ π
B. ∪ - σ π
C. ∪ ∩ × σ π
D. ∪ ∩ σ π
A.∪ - × σ π
B.∪ - σ π
C.∪ ∩ × σ π
D.∪ ∩ σ π
answer:A
A. ∪ - × σ π
B. ∪ - σ π
C. ∪ ∩ × σ π
D. ∪ ∩ σ π
A.∪ - × σ π
B.∪ - σ π
C.∪ ∩ × σ π
D.∪ ∩ σ π
answer:A