【单选题】【消耗次数：1】
消除了部分函数依赖的1NF的关系模式，必定是（ ） 。
①
1NF
②
2NF
③
3NF
④
BCNF
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相关题目
【简答题】
关系模式由2NF转化为3NF是消除了[填空]对码的[填空]。
【单选题】
3NF规范到BCNF，必须消除（ ）
①
非主属性对键的部分函数依赖
②
非主属性对键的传递函数依赖
③
主属性对键的部分和传递函数依赖
④
非平凡且非函数依赖的多值依赖
【单选题】
3NF规范到BCNF，必须消除（ ）
①
A.非主属性对键的部分函数依赖
②
B.非主属性对键的传递函数依赖
③
C.主属性对键的部分和传递函数依赖
④
D.非平凡且非函数依赖的多值依赖
【简答题】
2NF是在1NF的基础上消除非主属性对码的[填空1]。
【简答题】
有关系模式R(U,F)∈1NF，U=（A,B,C），若(A,B)→C，B→C，则该关系模式的规范化程度为[填空1]NF。
【简答题】
若关系模式R∈1NF，且每一个非主属性完全函数依赖于码，则称R∈[填空]。
【单选题】
有关系模式R（U,F）∈1NF，若R中任意的非平凡的函数依赖X→Y，X中均包含码，则关系模式R的规范化程度至少为( )。
①
A．2NF
②
B．3NF
③
C．4NF
④
D．BCNF
随机题目
【单选题】
The car salesman took the customer for a driver in the new model in order to ___ its improved features.
①
advocate
②
demonstrate
③
exhibit
④
reveal
【单选题】
I caught a___ of the car before it disappeared around the bend.
①
glance
②
glimpse
③
glare
④
stare
【单选题】
Alice ___her father that both she and her husband would be happy if he would live with them.
①
convinced
②
reinforced
③
pledged
④
required
【单选题】
Never in my wildest dreams ___ these people are living in such poor conditions.
①
I could imagine
②
?could I imagine
③
?I couldn’t imagine
④
?couldn’t I imagine
【单选题】
It was ___ back home after the experiments.
①
not until midnight did he go
②
until midnight that he didn’t go
③
not until midnight that he went
④
until midnight when he didn’t go
【判断题】
Mark often attempts to excape to be fined whenever he breaks traffic regulations.
①
正确
②
错误
【单选题】
The patients believe that the doctor knows exactly how to put them ___.
①
right
②
correct
③
perfect
④
well
【判断题】
It was because he was too clumsy to drive a car that Jim hadnt learned to drive.
①
正确
②
错误
【单选题】
Half of the workers here ___ under 30 ___.
①
is/years
②
are/year old
③
is/years old
④
are/years of age