CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
JAN2016
ASSESSMENT_CODE BT0066_JAN2016
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73048
QUESTION_TEXT
Explain magnetic disks along with its physical characteristics,
performance measures & optimization of disc block access.
Magnetic Disks
The magnetic disks facilitate the bulk of secondary storage. In the
modern computer systems the storage capacity requirements have been
growing at over 50 percent per year.
Physical Characteristics of Disks
SCHEME OF
EVALUATION
Each disk platter has a flat circular shape. Its two surfaces are covered
with a magnetic material, and information is recorded on the surfaces.
Platters are made from rigid metal or glass and are covered (usually on
both sides) with magnetic recording material. The disk surface is
logically divided into tracks, which are subdivided into sectors. A
sector is the smallest unit of information that can be read from or written
to the disk.
Performance Measures of Disks
The quality of a disk can be measured by its access time, capacity,
reliability and data-transfer-rate.
Access time is the time from when a read or write request is issued to
when data transfer begins.
4 Optimization of Disk-Block Access
In most of the operating system the disk I/O request generated by file
system and by virtual memory manager. Here the request provides
address on the disk and this address is in the form of a block number. A
block is a contiguous sequence of sectors from a single track of one
platter.
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
118244
QUESTION_TEXT
What are the update statements used in database? Explain.
Insert
Delete
SCHEME OF EVALUATION Update (1 mark)
Explain each with example 3*3=9 marks
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
163207
QUESTION_TEXT
Define database and list its various representative applications.
SCHEME OF
EVALUATION
Database: The database is a collection of related data. A data item is a
smallest named unit of data – for example first name, last name, ID
number. The applications make use of related data items as a single unit
is called a record. Examples of types of records are sales, item, product
and department.
Databases are extensively used for application. Following are the few
applications. Here are some representative applications:

Banking: For customer, accounts, and loans information, and
banking transactions.

Airlines: Applications to know reservations and schedule
information. Airlines were among the first to use databases in a
geographically distributed manner terminals situated around the world
accessed the central database system through phone lines and other data
networks.

Universities: For student information, course detailed
information, and grade report information.

Credit card transactions: For purchases and money withdrawal
on credit cards and generation of monthly statements.

Telecommunication: For keeping records of calls made,
generating monthly bills, maintaining balances on prepaid calling cards,
and storing information about the communication networks.

Finance: For storing information through application about
holdings, sales, and purchases of financial instruments such as stocks
and bonds.

Sales: For customer, product, logistic and purchase
information.

Manufacturing: For management of supply chain and for
tracking production of items in factories, inventories of items in
warehouses/ stores, and purchase orders for items.

Human resources: For information about employees, salaries,
payroll taxes and benefits, and for generation of paychecks.
QUESTION_TYPE DESCRIPTIVE_QUESTION
QUESTION_ID
163208
QUESTION_TEXT Explain the three level architecture of DBMS.
The Three Level Architecture of DBMS
SCHEME OF
EVALUATION
The database may be viewed differently at each level by defining three
level of abstraction as we discussed in the previous section. Fig 2.1
represents three-level architecture. It is said that DBMS also follow same
architecture in order to provide three levels of data. These three levels
are the external level, the conceptual level and the internal level.
Figure 2.1: The three level architecture for a DBMS
From the above figure 2.1 it is clear that view at each level described by a
schema. The description of database such as data entity definition and
their relationships with others are provided in the view called as schema.
Apart from this schema also provides information regarding the mapping.
The mapping is nothing but the interaction of entities at one level
abstraction to the next level. The overall design of the database is called
the database schema……………….
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
163209
QUESTION_TEXT
List and explain the relational database components.
Relational database components include:

SCHEME OF EVALUATION 
Table
Row

Column

Field

Primary key

Foreign key
QUESTION_T
DESCRIPTIVE_QUESTION
YPE
QUESTION_ID 163210
QUESTION_T
Explain the anomalies in a database.
EXT
Anomalies in a Database
Let us consider a relation schema regarding the information about an
employee of an organization.
EMP_PROJ(Ssn, Pnumber, Hours, Ename, Pname,Plocation)
Tuples of a relation on the relation schema EMP_PROJ(Ssn, Pnumber, Hours,
Ename, Pname, Plocation) are shown in Table 9.2. Figure 9.3 shows the
functional dependencies among its attributes. The key attributes of the
relation are Ssn, Pnumber. Function dependencies of the relation { Ssn,
Pnumber Hours, Ssn  Ename, Pnumber  Pname, Plocation}
Table 9.2: Employee Data Representation in Relation EMP_PROJ
SCHEME OF
EVALUATION
Attribute Ename is not functionally dependent on the whole key, but partially
depend on the one of the key namely Ssn. Similarly Pname and plocation
partially depends on attribute Pnumber. Only the attribute Hours is fully
functionally dependent on the key Ssn, Pnumber.
There are several undesirable problems in relation schema EMP_PROJ.
Redundancy: The objective of the database system is to reduce duplicate data being
stored in database, which in turn leads to waste of storage space, increases the size
of the data stored and also some time leads to inconsistencies among the data.
Whenever an update operation conducted on a database with high
redundancies this leads to inconsistent state which are explained below. Table
9.2 contain attributes Pname and Plocation of project are stored several times
where one of employee and another for project.
Update Anomalies: Update anomalies are occurs when multiple copies of same fact
exist in the database. This also leads to inconsistencies, when only some of many
copies are updated. Consider relation schema Figure 9.3 a change in the Plocation
of project number 2 made consistent in all the tuples related to project number 2. If
the update is not reflected one of the three tuples then there will be an
inconsistency in the data.
Insertion Anomalies: In the given relation schema we cannot enter only
project name & location for a given project number and this not meant for .
We need to have employee with proper SSN to him.
Deletion Anomalies: Given the project an individual employee wants to
discontinue, there is always possibility that we may lose information
regarding project name and its location. And this could happen if we maintain
single relation which maintains all these information in it. If we have another
relation for project information then deletion of any tuple from EMP_PROJ
will not cause any information lost.