题目内容

分析投保单关系模式属于第几范式，并简单说明原因。修改上述关系模式，以达至4NF。

查看答案

搜索结果不匹配？点我反馈

更多问题

请根据如下查询语句，回答问题(d)，(e)和(f)。SELECT客户号FROM订单，订单明细WHERE订单明细.订单号=订单.订单号AND产品号=’02’ AND数量＞10；(d) 上述查询语句的功能是什么请简要回答。(30个字以内)(e) 将上述查询语句转换成对应的关系代数表达式。(f) 上述SQL查询语句是否可以进一步优化如可以，给出优化后的SQL查询语句。

The desire to use language as a sign of national identityis a very natural one, and in result language has played a (1) prominent part in national moves. Men have often felt the (2) need to cultivate a given language to show that they aredistinctive from another race whose hegemony they resent. (3) At the time the United States split off from Britain, for (4) example, there were proposals that independence should belinguistically accepted by the use of a different language from (5) those of Britain. There was even one proposal that Americans (6) should adopt Hebrew. Others favoured the adoption ofGreek, though, as one man put it, things would certainly besimpler for Americans if they stuck on to English and made (7) the British learn Greek. At the end, as everyone knows, the (8) two countries adopted the practical and satisfactory solutionof carrying with the same language as before. (9) Since nearly two hundred years now, they have shown (10) the world that political independence and national identitycan be complete without sacrificing the enormous mutualadvantages of a common language. 7（）

国际贸易只包括世界各国之间货物交换的活动，是国际分工的表现形式。( )

A. 对
B. 错

请指出问题2中给出的读者、书目关系模式的主键，以及图书和借还记录关系模式的主键和外键。