U.G.C. NET Exam. Dec. 2020-June 2021 Paper II (COMPUTER SCIENCE & APPLICATIONS)

Total Questions: 100

61. Which of the DBMS component ensures that concurrent execution of multiple operations on the database results into a consistent database state?

Correct Answer: (d) Transaction processing system
Solution:

Transaction Processing System :- A transaction processing system (TPS) is a type of information system that collect, stores, modifies and retrieves the data transactions of an enterprise. In order to qualify as a TPS, transactions made by the system must pass the ACID test. The ACID tests refers to the following four requisites : -
1) Atomicity
2) Consistency
3) Isolation
4) Durability
TPS provides, Rapid response, continuous availability data integrity, Ease of use.
ex - Online transaction processing (OLTP), Real time transaction.

62. Consider following two statements:

Statement I: Relational database schema represents the logical design of the database. Statement II: Current snapshot of a relation only provides the degree of the relation.
In the context to the above statements, choose the correct option from the options given below:

Correct Answer: (a) Statement I is TRUE but Statement II is FALSE
Solution:

Degree of relationship represents the number of entity types that associated in a relationship. Types of degree are, unary, Binary, Temary, N- ary.

63. Given a fixed‐length record file that is ordered on the key field. The file needs B disk blocks to store R number of records. Find the average access time needed to access any record of the given file using binary search.

Correct Answer: (d)
Solution:log₂B

64. Given the following STUDENT‐COURSE scheme: STUDENT (Rollno, Name, courseno) COURSE (courseno, coursename, capacity), where Rollno is the primary key of relation STUDENT and courseno is the primary key of relation COURSE. Attribute coursename of COURSE takes unique values only. Which of the following query(ies) will find total number of students enrolled in each course, along with its coursename.

A. SELECT coursename, count(*) 'total' from STUDENT natural join COURSE group by coursename;
B. SELECT C.coursename, count(*) 'total' from STUDENT S, COURSE C where S.courseno=C.courseno group by coursename;
C. SELECT coursename, count(*) 'total' from COURSE C where courseno in (SELECT courseno f

Correct Answer: (a) A and B only
Solution:A and B only

65. Given the following STUDENT‐COURSE scheme: STUDENT (Rollno, Name, Courseno) COURSE (Courseno, Coursename, Capacity), where Rollno is the primary key of relation STUDENT and Courseno is the primary key of relation COURSE. Attribute Coursename of COURSE takes unique values only. The number of records in COURSE and STUDENT tables are 3 and 5 respectively. Following relational algebra query is executed: R=STUDENT X COURSE

Correct Answer: (a) A ‐III , B ‐I , C ‐IV , D ‐ II
Solution:

66. Answer the following question

Correct Answer: (a) (57, 53)
Solution:

67. Given a relation scheme R(x,y,z,w) with functional dependencies set F={x y, z w}. All attributes take single and atomic values only.

A. Relation R is in First Normal FORM
B. Relation R is in Second Normal FORM
C. Primary key of R is xz
Choose the correct answer from the options given below: 

Correct Answer: (c) A and C only
Solution:A and C only

68. A company is consuming parts in the manufacturing of other products. Each of the part is either manufactured within the company or purchased from the external suppliers or both. For each part, partnumber, partname is maintained. Attribute batchnumber is maintained if the consumed part is manufactured in the company. If part is purchased from external supplier, then supplier name is maintained. Which of the following constraints need to be considered when modelling class/subclass concepts in ERD for the given problem.

Correct Answer: (a) Total specialization and overlapping constraints
Solution:Total specialization and overlapping constraints

69. A transaction may be in one of the following states during its execution life cycle in concurrent execution environment.

A. FAILED
B. TERMINATED
C. PARTIALLY COMMITTED
D. COMMITTED
E. ACTIVE
Given a transaction in active state during its execution, find its next transitioned state from the options given below:

Correct Answer: (b) Either A or C only
Solution:Either A or C only

70. Which of the following is used to create a database schema?

Correct Answer: (b) DDL
Solution:

The DDL commands in SQL are used to create database schema and to define the type and structure of the data that will be stored in a data base. Sql DDL commands are further divided into the following major categories : create, alter, drop, truncate.