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_爱下问搜题

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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。

选择题

下列物质加热后没有固体生成的化学变化是（　　）

①氯酸钾； ②铜； ③水； ④氧化汞； ⑤碱式碳酸铜．

A．①②

B．④

C．④⑤

D．③④⑤

完形填空

完形填空（共20小题；每小题1分，满分20分）
阅读下面短文，从短文后所给各题的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项。
Dad was not only my best friend, but my compass. While he was alive, he  1   me with his actions and advice. He taught me one important  2  “Believe in yourself.”
If there was one phrase my dad  3  liked to hear, it was “I can’t.” He never got to finish high school and 4 two jobs to support his family,  5   he never complained. Through education and years of hard work, my dad became an excellent journalist.
When I was in high school, I had a  6  time with math. He tried to help me, but I 7 struggled. So my math teacher suggested I meet with him at 7:00 each morning before school for  8  help. I told my dad, “That’s  9 ! I can’t do that!” He replied, “You’re doing it. I’ll sent you to school.” Every morning at 6:45 a.m., we’d leave the  10 . Despite working 12 hours every day, Dad never once  11   driving me to school.
After months of  12  , I was facing the final exam. I was so  13 . On the day of the final, my dad hugged me and said, “Luke,  14   yourself. You can do it.” His words made me realize I needed to trust in my  15  and in the hours of work I’d 16 . When I got my  17   proudly, the first person I called was Dad. He screamed, “Yes! You deserved it!”
Even now, whenever I  18  that a task is too much for me, I think back to that exam. No matter how  19   something is, if you’re willing to work, you can succeed. I’m forever 20  to Dad for that lesson.

D．interviewing

D．interesting