12131_数据库_A1
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天津大学试卷专用纸
学院
计算机科学与技术
专业
计算机科学与技术
班 年级 学号 姓名 共 8 页 第 1 页
2012～2013 学年第 1 学期期末考试试卷
《数据库原理》（A 卷 共 8 页）
（考试时间：2013 年 1 月 10 日）
题号 一 二 三 四 五 六 成绩 核分人签字
得分
一、选择题（20 分）
1. What does the abbreviation DBA stand for in the database technology? ( )
A. DataBase Administrator B. DataBase Administration
C. DataBase Application D. DataBase Analyst
2. What one of
the
following options is not a part of a data model? ( )
A. physical storage of data B. structure of data
C. operations on the data D. constraints on the data
3. Which one of the following data models was proposed by E. F. Codd in his 1970's
paper “A Relational Model of Data for Large Shared Data Banks”?
( )
A. hierarchical data model B. network data model
C. relational data model D. object-oriented data model
4. Given two relations R(A, B) and S(A, B) have schemas with identical sets of attributes,
and the domains for each attribute are the same. Which of the following equations of
the relational algebra expressions hold? ( )
I.
()
R
SRRS II. ()
R
SS SR III.
R
SR
S
A. I. only B. I. and II.
C. I., II. and III. D. None of the above
5. Consider relations
R
(
A
,
B
) and
S
(
B
,
C
) where the current instance of
R
has 5000
tuples and the current instance of
S
has 3000 tuples. The primary key of
S
is
B.
The
expected number of tuples in
R
S is
( )
A. Less than or equal to 3000 B. Less than or equal to 5000
C. Greater than 3000 D. Greater than 5000
6. Given a relation
R
(
A
,
B
,
C
), the functional dependency
AB
→
C
holds on
R
. If
(
a
1
,
b
1
,
c
1
), (
a
2
,
b
2
,
c
2
), (
a
1
,
b
1
,
c
3
), (
a
1
,
b
2
,
c
4
) are four tuples of
R
and we know
a
1
a
2
and
b
1
b
2
, then which one of the following equations must hold? ( )
A.
c
1
=
c
2
B.
c
1
=
c
3
C.
c
1
=
c
4
D.
c
2
=
c
4
7. Given two relations
R
(
A
,
B
) and
S
(
C
,
D
), the following clause is in the CREATE
TABLE statement of the relation
S
: FOREIGN KEY (D) REFERENCES R(A)
R
has two tuples (1, 2) and (2, 3).
Which of the following tuples cannot occur in
S
? ( )
A. (1, 2) B. (2, 3) C. (2, 1) D. (2, NULL)
8. Which one of the following statements about virtual views is
not
correct? ( )
A. Virtual views in some cases can be modified.
B. Virtual views may be queried as if it were a stored table.
C. Virtual views also have tuples that are physically stored.
D. Virtual views are defined by a query over other relations.
9. Consider a database that has an element
A
whose initial value is 5. The following
table shows actions of a transaction T and its corresponding undo log records. If after
step 4),
T
is completed and about to commit. Which is the correct action at step 5)?
Step Action Log
1) <START T>
2) READ(A,t)
3) t := t*2
4) WRITE(A,t) <T, A, 5>
5) ?
A.
WRITE(A, t)
B.
INPUT(A)
C.
OUTPUT(A)
D.
FLUSH LOG
10. Suppose
T
1
and
T
2
are two transactions, and
A
is a database element. Which of the
following statements about database locking is
not
correct? ( )
A.
If T
1
has already held an exclusive lock on A, then T
2
cannot obtain a shared lock on A.
B.
If T
1
has already held a shared lock on A, then T
2
can obtain a shared lock on A.
C.
If T
1
has already held an exclusive lock on A, then T
2
cannot obtain an exclusive lock on A.
D.
If T
1
has already held a shared lock on A, then T
2
can obtain an exclusive lock on A.
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