题目内容

设有关系模式只(C,P,S,G,T,W),各属性含义为:C课程,P老师,S学生,G成绩,T时间,W教室,其函数依赖集为:F=C→P,(S,C)→G,(T,W)→C,(T,P)→W,(T,S)→W则关系模式的关键字为 (35) ,R的规范化程度最高可达到 (36) 。若将R分解为关系模式组R1 (C,P),R2(S,C,G),R3(S,T,W,C),则R1,R2,R3的规范化程度最高分别可达到 (37) , (38) , (39) 。 (37)处填()。

A. 2NF
B. 3NF
C. BCNF
D. 4NF

查看答案
更多问题

假设字符a,b,c,d,e,f的应用频率分别是0.07,0.09,0.12,0.22,0.23,0.27,则c的Huffman(哈夫曼)编码为()。

A. 001
B. 0000
C. 0001
D. 11

阅读下面材料,根据要求写一篇论说文。我们的人生,就像大海里的航船,只要不停止航行,就会遭遇风险。没有风平浪静的海,没有不受伤的船。[要求] 用规范的现代汉语写作。立意自定,题目自拟;观点明确,分析具体,条理清楚,语言流畅。不少于800字。

设有关系模式只(C,P,S,G,T,W),各属性含义为:C课程,P老师,S学生,G成绩,T时间,W教室,其函数依赖集为:F=C→P,(S,C)→G,(T,W)→C,(T,P)→W,(T,S)→W则关系模式的关键字为 (35) ,R的规范化程度最高可达到 (36) 。若将R分解为关系模式组R1 (C,P),R2(S,C,G),R3(S,T,W,C),则R1,R2,R3的规范化程度最高分别可达到 (37) , (38) , (39) 。 (38)处填()。

A. 2NF
B. 3NF
C. BCNF
D. 4NF

The grid computing is a new (66) technology connecting the distributed and (67) resources to the high-speed network and integrating a super-computer of processing capacity. The significance and architecture of the grid computing is explained. Several kernel technology such as OGSI, resource management, task management, task scheduling, high rate communication and security are described. Aiming at the particularity of the grid computing environment a mechanism similar to the technology of the search engine is designed to registry, discovery and (68) the resources in the grid. The whole model of the resource management is built by connecting task manager in the local resource management system to others with P2P model. The task may migrate among the task managers in order to (69) the load. The task users summit may be executed in relatively tight resource set, which will not only decrease the total communication overheads of the whole task but also (70) the performance of the system. (70)处填()。

A. decrease
B. enhance
C. keep
D. balance

答案查题题库