First, multiple-choice questions (20 points)
1, database, database system and database management system.
The system is _ _ _ a _ _ _
A. database system includes database and database management system.
C.DB includes DBS and DBMS D. DBS is DB and DBMS.
2. Relational data model _ _ _ d _ _.
Only the 1: 1 relationship between entities can be expressed.
B can only represent 1:n connection between entities.
C. only the m:n relationship between entities can be expressed.
D can represent the above three relationships between entities.
3. In the database, the following statement _ _ a _ _ is incorrect.
The database avoids the duplication of all data.
B. If the system is completely controllable, the system can guarantee the consistency when updating.
The data in the C database can be * * *
Three-dimensional database reduces data redundancy.
4. In the database, the root cause of data inconsistency is __C__.
A. The data storage capacity is too large
B. Data is not strictly protected
C. data integrity control is not performed.
D. Data redundancy
5. In the three-level schema structure of the database, it is __D__ that describes the global logical structure and characteristics in the database.
A. external mode B. internal mode C. storage mode D. mode
6. The division of the three-level schema architecture of the database is conducive to maintaining the _ _ A _ _ of the database.
A. Database independence B. Data security
C. Structural standardization D. Operational feasibility
7. Let the relationship between R and S be binary, then express it in tuples:
{t | ($u) ( $v) (R(u)？ S(v)？ u[ 1]=v[ 1]？ t[ 1]=v[ 1]？ t[2]=v[2])}
The equivalent relational algebraic expression is _ _ _ _ _ _ _.
A.p3，4(R？ s)b . p . 2，3(R？ s)
1= 1
c . p . 3，4(R？ S) D.p3，4(s 1= 1(R？ s))
1= 1 8. What is the relationship between all levels of the relational model? ____。
A.3NF？ 2NF？ 1NF B. 3NF？ 1NF？ 2NF
C. 1NF？ 2NF？ 3NF D. 2NF？ 1NF？ 3NF
9. Blocking mechanism in database is the main method of _ _ C _ _.
A. integrity B. security C. concurrency control D. recovery
10. In database design, E-R diagram is used to describe the information structure, but it does not involve the representation of information in the computer. it is
_ _ b _ _ stage of database design.
A. Requirements analysis B. Conceptual design C. Logical design D. Physical design