问题 单项选择题

设有两个数据库表,父表和子表之间是一对多的联系,为控制子表和父表的关联,可 以设置“参照完整性规则”,为此要求这两个表______。

A.在父表连接字段上建立普通索引,在子表连接字段上建立主索引

B.在父表连接字段上建立主索引,在子表连接字段上建立普通索引

C.在父表连接字段上不需要建立任何索引,在子表连接字段上建立普通索引

D.在父表和子表的连接字段上都要建立主索引

答案

参考答案:B

解析:参照完整性是指当插入、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。 当有两个数据库表,父表和子表之间是一对多的联系,可以通过设置“参照完整性规则”来控制父表和子 表的关联。在关系数据库中是通过连接字段来体现和表示联系。连接字段要在父表中做为主关键字,在子表中是外部关键字,为此要求这两个表在父表连接字段上建立主索引,在子表连接字段上只要建立普通索引就可以了。

阅读理解

Since 1989, Dave Thomas, who died at age 69, was one of the most recognizable faces on TV. He appeared in more than 800 commercials (商业广告) for the hamburger chain named for his daughter. “As long as it works," he said in 1991, “I'll continue to do those commercials."

Even though he was successful, Thomas remained troubled by his childhood. “He still won't let anyone see his feet, which are out of shape because he never had

properfitting shoes," Wendy said in 1993. Born to a single mother, he was adopted(收养) as a baby by Rex and Auleva Thomas of Kalamazoo in Michigan. After Auleva died when he was 5, Thomas spent years on the road as Rex traveled around seeking construction work. “He fed me," Thomas said, “and if I got out of line, he'd beat me."

Moving out on his own at 15, Thomas worked, first as a waiter, in many restauran

ts. But he had something much better in mind. “I thought if I owned a restaurant," he said, “I could eat for free." A 1956 meeting with Harland Sanders led Thomas to a career as the manager of a Kentucky Fried Chicken restaurant that made him a millionaire in 1968.

In 1969, after breaking with Sanders, Thomas started the first Wendy's Old Fashi

oned Hamburgers, in Columbus, Ohio, which set itself apart by serving made to order burgers. With 6,000 restaurants worldwide, the chain now makes$ 6 billion a year in sales.

Although troubled by his own experience with adoption, Thomas, married since 1954 to Lorraine, 66, and with four grown kids besides Wendy, felt it could offer afuture for other children. He started the Dave Thomas Foundation (基金会) for Adoption in 1992.

In 1993, Thomas, who had left school at 15, graduated from Coconut Creek High School in Florida. He even took Lorraine to the graduation dance party. The kids voted him Most Likely to Succeed.

“The Dave you saw on TV was the real Dave,"says friend Pat Williams. “He wasn't a great actor or a great speaker. He was just Joe Everybody."

1.What is the article mainly about?

A. The life of Dave Thomas.              B. The dream of Dave Thomas.

C. The schooling of Dave Thomas.          D. The growth of Dave Thomas's business.

2. What do we know about his childhood?

A.He lived a poor life.                  B.He had caring parents.

C.  He stayed in one place.              D.  He didn't go to school.

3.Choose the right time order of the following events in Thomas's life.

a.graduated from high school         b.started his own business

c.became a millionaire               d.started a foundation

e.met Harland Sanders

A. e,b,c,d,a,    B. a,e,c,b,d,      C. e,c,b,d,a,    D. a,e,b,c, 

4. “He was just Joe Everybody." (in the last paragraph) means  _______.

A. Dave was famous               B. Dave was ordinary

C. Dave was showy                D. Dave was shy 

5.What is the name of Dave Thomas's business?

A. Thomas's.         B. Wendy's.         C. Lorraine's.         D. Rex's. 

单项选择题