A.(Sno,Cname,Grade)→(Cname,Crade)
B.(Sno,Cname)→(Cname,Grade)
C.(Sno,Cname)→(Sname,Grade)
D.(Sno,Sname)→Sname
[多选题]下面哪几个依赖是平凡函数依赖()。A.(Sno,Cname,Grade)→(Cname,Crade)B.(Sno,Cname)→(Cname,Grad
[单选题]下面( )成立时,称X→Y为平凡的函数依赖。A.XYB.YXC.X∩Y=D.X∩Y=
[单选题]下面哪一个依赖是平凡依赖()。A .SnoCnameGrade→SnoGradeB .SnoCname→CnameGradeC .SnoCname→SnameGradeD . D.以上答案都不是
[单选题]下列函数依赖中______是平凡的FD。A.AB->BCB.AB->CDC.AB->AD.AB->D
[单选题]下列函数依赖中( )是平凡的FD。A.AB→BCB.AB→CDC.AB→AD.AB→D
[单选题]下列约束中能确保一个函数依赖是完全非平凡函数依赖的是______。A.仅当其右边的属性集是左边属性集的子集______。B.仅当其右边属性集中的属性都不属于左边的属性集C.仅当其右边属性集中至少有一个属性不属于左边的属性集D.仅当其右边属性集中的属性都属于左边的属性集
[单选题]下列不属于非平凡函数依赖的是______。A.(CustomerID,ProviderID,BuyDate)→GoodsNameB.(CustomerID,ProviderID,BuyDate)→GoodsName,ProviderIDC.(CustomerID,ProviderID,BuyDate)→GoodsClassIDD.(CustomerID,ProviderID,BuyDate)→ProviderID
[单选题]下列不属于非平凡函数依赖的是______。A.(CustomerID, ProviderID, BuyDate)→Good-sNameB.(CustomerID, ProviderID, BuyDate)→Good-sName, ProviderIDC.(CustomerID, ProviderID, BuyDate)→Good-sClassIDD.(CustomerID, ProviderID, BuyDate)→ProviderID