问题 单项选择题

通过指定字段的数据类型和宽度来限制该字段的取值范围,这属于完整性中的( )。

A.域完整性

B.字段完整性

C.参照完整性

D.实体完整性

答案

参考答案:A

解析: 域完整性也称为字段有效性规则,在插入或修改字段值时被激活,主要用于数据输入正确性的检验,可以限定字段取值类型和取值范围。实体完整性是保证表中记录惟一的特性,利用主关键字或候选关键字来实现。参照完整性与表之间的关联有关。它的大概含义是:当插入、删除或修改一个表中的数据时,通过参照引用相互关联的另一个表中的数据,来检查对表的数据操作是否正确。

单项选择题
阅读理解

Everyone agrees that all the creatures want happiness and are afraid of pain and grief. The question, however, is “What is real happiness?” The desire for happiness has no meaning without understanding the real nature of happiness.

Generally, ordinary beings consider sensual(感觉的) pleasures as happiness, and their actions are directed toward gaining these. According to them, searching for happiness means searching for pleasures of the senses. The question, “What is happiness?”, does not arise(出现) in their hearts, because in their hearts they think of a life full of sensual joys as a happy life.

Some thinkers say, “Happiness does not lie in the objects of enjoyment; happiness or unhappiness lies in the imagination.” To prove their belief they give examples like the following one. A man has a two-storey house. When he thinks of those who have a house with three storeys or more, he feels unhappy. When he thinks of those who have just a cottage, he feels happy. Such happiness does not lie in possessions(占有物), but in the imagination. They advise people to take inspiration from those who have few possessions but are quite happy. If you only consider people wealthier than yourself, you will always be unhappy.

If you want to be happy, they say, look at the poor. But it is unreasonable to hold that happiness lies in the imagination. And it is inappropriate to think that someone is happy if he only imagines himself better than the poor and the unhappy. This attitude also satisfies the sense of pride of possession. This can never be called happiness. Unless we find out where happiness lies, we cannot really become happy.

Some ask people to do this or that, and say, “This way your desires will be satisfied. That way you will get what you want and become happy.” People holding these views regard happiness as satisfaction of desires and unhappiness as denial(否定) of such satisfaction.

小题1:What kind of life can make common people feel happy?

A.Life without pain and grief.

B.Life full of sensual pleasures.

C.Life with desire for possessions.

D.Life full of imagination.小题2:The underlined word “cottage” in Paragraph 3 probably refers to ________.

A.a house in one’s imagination

B.a modern building

C.a desired object

D.a small house小题3:The author may agree that ________.

A.by comparing themselves with the poor, people will feel happy

B.people won’t feel happy without a desire for happiness

C.possessing wealth may lead to a sense of pride

D.people have to experience pain and grief before finding happiness小题4:The best title for this passage would be “________”.

A.What Is Happiness?

B.How to Get Happiness

C.Happiness and Desire

D.Happiness and Imagination