上海财经大学数据库系统课程考试卷（A）
2005——2006学年第二学期
姓名学号班级得分
1.True or False. (20 points)
1).External/Conceptual Mapping is the key to physica
l data independence.
2).DA is the person who provides the necessary techn
ical support for implementing those decisions.
3).It is the job of the DML processor to choose an e
fficient way to implement user’s request.
4).Relational data model represents the data in a da
tabase as a collection of tables.
5).Indexes allow the database management system to d
irectly access the rows of the table on which the index has b een defined.
6).Since the logical data structures are intended fo
r the application programmers, the database designer is not i nvolved in their development.
7).Views are only descriptions of data. They are not
real tables.
8).Denormalization causes the redundant storage of i
nformation.
9).Horizontal splitting of a relational variable alw ays creates relational variables for different primary key ra nges of the original relational variable.
10).For an unordered retrieval request, different executi ons of the request may return the retrieved rows in a differe nt sequence.
11).A relationship type can again be the source or target of a relationship type.
12).A business relationship type can always be translated into a relationship type of the entity-relationship model fo r the application domain.
13).The updating of redundant information for violations of the Third Normal Form cannot be controlled by triggers.
14).SQL does not permit users to define their own types, columns must be defined in terms of built-in types only.
15).Once a transaction commits, its updates may not survi ve in the database when there is a subsequent system crash.
16).Any transaction which was in progress at the time of the system failure must be redo at restart time.
The checkpoint record gives a list of all transactions th at were in progress at the time the checkpoint was taken.
If transaction A holds an S lock on tuple t, then a reque st from some distinct transaction B for a X lock on t will be denied.