()是项目产品投入使用或者项目交付结果进入运行期的开始。
职工表中的婚姻状态字段是逻辑型,执行如下程序后,最后一条命令显示的结果是( )。
A、T
B、F
C、已婚
D、未婚
下面程序运行后,输出的结果是( )。
A、
B、
C、
D、
Which three statements correctly describe the functions and use of constraints? ()
AConstraints provide data independence.
BConstraints make complex queries easy.
CConstraints enforce rules at the view level.
DConstraints enforce rules at the table level.
EConstraints prevent the deletion of a table if there are dependencies.
FConstraints prevent the deletion of an index if there are dependencies.
Which of the following statements is true regarding the VERSIONS BETWEEN clause?()
A、 The VERSIONS BETWEEN clause may be used in DML statements.
B、 The VERSIONS BETWEEN clause may be used in DDL statements.
C、 The VERSIONS BETWEEN clause may not be used to query past DDL changes to tables.
D、 The VERSIONS BETWEEN clause may not be used to query past DML statements to tables.
企业信息系统往往是一个具有业务复杂性和技术复杂性的大系统,针对其建设,系统分析首先要进行的工作是(1)。系统开发的目的是(2)。空白(2)处应选择()
A、获得当前系统的物理模型
B、抽象出当前系统的逻辑模型
C、建立目标系统的逻辑模型
D、建立目标系统的物理模型