Relation R:A B C Relation S:B C D
1 2 3 2 3 4
6 7 8 2 3 5
9 7 8 7 8 1
The number of tuples that the result of the expression R∞S(Here if natural join of relations R and S) is (69) .(69)
A.1
B.4
C.7
D.10
[单选题]Let R and S be the relation respectively: Relation R: A B C Relation S: B C D 1 2 3 2 3 4 6 7 8 2 3 5 The number of tuplesthat the result of the expression R ∞ S (Here is the natural join of relations R and S) isA.3B.4C.6D.9
[单选题]Let R and S be the following relations:A.3B.4C.5D.6
[单选题]F.or relation R where primary key contains multiple, no non-key attribute should be functionally dependent on a part of the primary key.This relation R is at least inA.1NFB.2NFC.3NFD.BCNF
[单选题]Suppose we have the relation schema R(A,B,C,D)with functional dependencies;F{A→B,B→C,C→D,D→A},then R(A,B,C,D)at least is inA.1NFB.2NFC.3NFD.BCNF
[单选题]Suppose we have the relation schema R(A,B,C,D)with functional dependencies;F{A→B,B→C,C→D,D→A},then R(A,B,C,D.at least is in (73) .(73) A.1NFB.2NFC.3NFD.BCNF
[单选题]F.or relation R where primary key contains multiple attributes,no non-key attribute should be functionally dependent on a part of the primary key. This relation R is at least inA. 1NFB.2NFC.3NFD.BCNF
[单选题]C.onsider a relation R ( A,B,C,D ) with the following dependencies: AB ? C, CD ? E, DE ?B.A.ABB.ABCC.ABDD.ABE
[单选题]Let's ______.A.play footballB.play a footballC.play the footballD.play foot
[单选题]( )–It’s raining heavily.Let’s stand under that big tree.–__________.It’s very dangerous to do so in such weather.A.We don’t have toB.Let’s goC.All rightD.We’d better not
[单选题]Let’s ___ play in the street . Father tells me ____ do so.A. not to ….. not toB. not …not toC. don’t , to notD. not to …don’t