问题 单项选择题

在Visual FoxPro中,假定数据库表S(学号,姓名,性别,年龄)和SC(学号,课程号,成绩)之间使用"学号"建立了表之间的永久联系,在参照完整性的更新规则、删除规则和插入规则中选择设置了"限制"。如果表S所有的记录在表SC中都有相关联的记录,则【 】。

A.允许修改表S中的学号字段值

B.允许删除表S中的记录

C.不允许修改表S中的学号字段值

D.不允许在表S中增加新的记录

答案

参考答案:C

解析:数据库表之间的参照完整性规则包括级联、限制和忽略,如果将两个表之间的更新规则、插入规则和删除规则中都设置了"限制",则不允许修改两表之间的公共字段。

阅读理解

根据短文内容,按要求答题。

    Television has now come to nearly every family. It has become a very important part in people's life.

School children in some cities watch TV about twenty hours a week. 

     Some people believe that television is good for children because it helps them learn about their country

and the world. With the help of programmes of education, children do better in school.

     Other people feel that there are too many programmes about love and crime on TV, and that even

programmes of education don't help children a lot. Children simply watch too much television, so they

don't do a lot of other important things for their education.

     Children of three to six learn to speak their own language and talk with people. When they are watching

TV, they are only listening to the language, and they aren't talking with anyone. When school children watch

TV, they read less. Because of this they don't learn to read or write quickly at school. All children learn by

doing, and they need time to play in order to learn about the world. When they watch TV, they play less.

They also have less time to do with their parents and friends, and they have less time to have sports.

     Recently, a hundred and fifteen families in a middle school decided to stop watching for a month or more.

At first it was difficult, but there were soon a lot of good changes. The children read, played, and exercised

more and the family became full of joy. But at the end of the month all the families began to watch TV as

much as before. Not one family was able to give up television completely.

1. Why does television become a very important part for school children in some cities?

                                                                                                                                                         

2. According to this article, what good things do television programmes help children to learn about?

                                                                                                                                                         

3. Give the two reasons against children's watching TV in Paragraph 3. 

                                                                                                                                                         

4. It is true that all children learn by doing. What do children need to do for their healthy personal growth?

                                                                                                                                                         

5. What is the best title for this passage (短文)?

                                                                                                                                                         

填空题