【名词&注释】
设计阶段(design stage)、数据模型(data model)、不一致(inconsistency)、传递函数依赖(transitive functional dependency)
[单选题]在关系模式R(U,F)中,X、Y、Z都是属性,且X→Y、Y→Z,则X→Z是()
A. 一定是传递函数依赖(transitive functional dependency)
B. 一定不是传递函数依赖(transitive functional dependency)
C. 不一定是传递函数依赖(transitive functional dependency)
D. 如果X是单一属性,则是传递函数依赖(transitive functional dependency)