问题
单项选择题
要控制两个表中数据的完整性和一致性可以设置“参照完整性”，要求这两个表 ______。
A．是同一个数据库中的两个表
B．是不同数据库中的两个表
C．是两个自由表
D．一个是数据库表，另一个是自由表
答案
参考答案：A
搜题请搜索小程序“爱下问搜题”
要控制两个表中数据的完整性和一致性可以设置“参照完整性”，要求这两个表 ______。
A．是同一个数据库中的两个表
B．是不同数据库中的两个表
C．是两个自由表
D．一个是数据库表，另一个是自由表
参考答案：A
People live in different houses. You may know a wooden house or a paper house. But do you know a(n) 1 house? In 2008, the first ice house in North America opens its 2 to welcome some visitors. The floors, windows and walls are all made of ice. It has ten bedrooms 3 twenty people can stay there each night. Visitors to the house 4 in ice beds, sit on ice chairs and eat from ice plates. Well, the toilets are not made of ice, of course. It’s usually below zero so it is very 5 inside the house. However, do the visitors just sit there to 6 warm? No, visitors have to 7 special clothes. These can make 8 feel warm until morning. Workers 9 about four weeks designing the ice house. Visitors can only stay in this ice house in winter. It isn’t 10 in hot summer. Because this house is so special, it is becoming popular with young people.
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