【单选题】若对一个具有一对多关联的表“实施参照完整性”,并且“级联更新相关字段”,则( )
A.
在子表中更改子关键字的值,将同时更新主表中所有相关记录的匹配值
B.
在主表和子表中同时更新关键字的值,将同时更新所有相关记录的匹配值
C.
在主表或子表中更新关键字的值,将更新所有相关记录的匹配值
D.
在主表中更改主关键字的值,将同时更新子表中所有相关记录的匹配值
【单选题】Not until most of the people had left the airport __________his sister was there.
【判断题】PLC控制器输入_IO_EM_DI_00变量的状态不能由程序决定,只能由输入端子决定。 ( )
【简答题】It was not until be arrived at the station ________ he realised he had forgotten his ticket. A) that B) before C) when D) after
【简答题】II 型系统对数幅频特性的低频段渐近线斜率为( )
【单选题】II型系统对数幅频特性的低频段渐近线斜率为
【判断题】国旅、中旅和青旅三大旅行社系统所接待的海外旅游者占当年来华旅游的有组织海外旅游者总人数的90%,基本上垄断了中国的旅游市场。
【单选题】Not until he left his home ______ to know how important the family was for him.
【单选题】 企业从目前的经营领域和基础水平收缩和撤退、且偏离战略起点较大的战略是( )
【单选题】Not until he left home ______ to know _______ important the family was for him.