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问题 单项选择题

在Visual FoxPro中进行参照完整性设置时，要想设置成：当更改父表中的主关键词段或候选关键词段时，自动更改所有相关子表记录中的对应值。应选择 ______。

A．限制(Restric

B．忽略(Ignor

C．级联(Cascad

D．级联(Cascad或限制(Restric

答案

参考答案：C

解析：
参照完整性设定的规则如下表所示。
　　　　　　　　　　　　　　　　参照完整性设定的规则

选项卡
选项按钮		更新删除插入
级联用父表中新的关键词更新子表的相关记录删除父表中的记录时，会自动删除子表的相关记录无
限制如果子表中有相关记录，则禁止更新如果子表中有相关记录，则禁止删除如果父表中没有匹配的记录，则在子表中禁止插入
忽略允许父表更新，与子表无关允许父表删除，与子表无关允许子表插入，与父表无关

选择题

被誉为“裸子植物的故乡”的国家是（　　）

A．中国

B．俄罗斯

C．美国

D．日本
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单项选择题

There has been much speculation about the origin of baseball. In 1907 a special commission decided that the modern game was invented by Abner Doubleday in 1839. One hundred years later the National Baseball Museum was opened to honor Doubleday. Historians, however, disagree about the origin of baseball. Some say that baseball comes from bat-and-ball games of ancient times. It is a matter of record that in the 1700s English boys played a game they called "baseball". Americans have played a kind of baseball since about 1800. At first tile American game had different rules and different names in various parts of the country — "town ball". "rounders", or "one old cat". Youngsters today still play some of these simplified forms of the game.
Baseball did not receive a standard set of rules until 1845, when Alexander Cartwright organized the Knicker-bocker Baseball Club of New York City. The rules Cartwright set up for his nine-player team were widely adopted by other clubs and formed the basis of modem baseball. The game was played on a "diamond" infield with the bases 90 feet apart. The first team to score 21 runs was declared the winner. By 1858 the National Association of Baseball Players was formed with 25 amateur teams. The Cincinnati Red Stockings began to pay players in 1869.

Which of the following was NOT a predecessor of baseball

A. Rounders.



B. Town ball.
C. Cricket.



D. One old cat.
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