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DRIVE- FALL DRIVE 2013
PROGRAM/SEMESTER- MBADS – (SEM 3/SEM 5) / MBAN2 / MBAFLEX
– (SEM 3) / PGDISMN – (SEM 1)
SUBJECT CODE & NAME- MI0034- DATABASE MANAGEMENT
SYSTEMS
Q1. How is DBMS classified based on several criteria?
Explain each one of them with few examples where ever required
(Listing the criterion-3 marks, Explaining the types
based on each criterion-6 marks, Example-1 marks) 10 marks
Answer.
Classification and Criterion of
Database Management Systems
Several criteria are normally
used to classify DBMS.
A. Based on Data model
B. Based on number of users
C. Based on number of sites.
A. Based on Data model: It
specifies a particular mechanism for data storage and retrieval. The primary
difference between the different database models lies in the methods of
expressing relationships and constraints among the data elements. Five database
models are discussed here:
1. Hierarchical Model: It
is one of the oldest database models [1950s], and represents data as
hierarchical tree structures.
2. Network Model: It
represents data as record types, and has an ability to handle many-to-many
relationships.
3. Relational Model: Relational
models stores data in the form of a table. Data is interrelated; relationships
link rows from two tables.
End-users need not know about
physical data storage details. So it is conceptually simple.
Q2. Differentiate between B+ tree and B- tree. Explain
them with diagrams
(2 Diagrams-4 marks, Explanation based on comparison-6
marks) 10 marks
Answer.
B + Tree Index Files
The main disadvantage of the
index-sequential file organization is that performance degrades as the file
grows. A B+-tree index takes the form of a balanced tree in which every path
from the root of the tree to a leaf of the
tree is of the same length.
In a B- tree every value of the
search field appears once at some level in the tree, along with a data pointer
[may be in internal nodes also]. In a B+-tree, data pointers [address of a
particular search value] are stored only at the leaf nodes of the tree; hence,
the structure of leaf nodes differs from the structure of internal nodes. The
leaf nodes have an entry for every value of the search field, along with a data
pointer to the record. A B+ tree is a multilevel index, but it has got
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Q3.
EMPLOYEE
DEPARTMENT
Using
these tables answer the following question
a.
If we want to see all the employees with salary between 40000 and 50000,
which query can be used?
b.
Select employee name from EMPLOYEE table, whose name starts with R
c.
Explain aggregate functions and grouping in detail
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( a.
Query based in BETWEEN operator
SELECT * from employee
WHERE salary between 40000 to 50000 -2 marks,
b. Query based in LIKE
condition
SELECT * from employee
WHERE Name LIKE ‘r%’; -3 marks,
c. Explaining aggregate
functions on select statement, with an example, showing the output of the
query, explaining having clause, with example -5 marks) 10 marks
We'll briefly describe most of the query types, although in this course we'll focus on the most commonly used query type, the select query. A select query retrieves data from one or more tables and displays the recordset in a datasheet. You can also use a select query to group data, and to calculate sums, counts, averages, and other types of totals, although we won't cover calculations in this course. |
Q4. What are the problems and failures that may
encounter with respect to the transactions in a database management system?
Give examples.
(Explaining the three problems with code-6 marks,
Listing the types of failures (at least 4)-4 marks) 10 marks
Answer.
We now discuss the types of
problems we may encounter when these two transactions run concurrently.
1. The lost update problem: Suppose transactions T1 and T2
are submitted at the same time, when these two transactions are executed concurrently
as shown in fig. a, then the final value of x is incorrect. Because T2 reads
the value of x before T1 changes it in the database, and hence the updated
value resulting from T1 is lost. For e.g.: x=80 at the start (80 reservation at
the beginning), n=5 (T1 transfers 5 seat reservation from the flight x to y),
and m=4 (T2 reserves 4 seats on x), the final result should be x=79 but due to
interleaving of operations x=84, because updating T1 that removed the 5 seats
from x was lost.
T1 T2
5. Consider any database of your choice (may be simple
banking database/forecasting database/project management database). Show the
deduction of the tables in your database to the different types of normal forms
(Choosing a proper database-2 marks, Explaining the 5
normal forms with respect to the database chosen-8 marks) 10 marks
Answer.
Normal forms Based on Primary
Keys
A relation schema R is in first
normal form if every attribute of R takes only single atomic values. We can
also define it as intersection of each row and column containing one and only
one value. To transform the un-normalized table (a table that contains one or
more repeating groups) to first normal form, we identify and remove the
repeating groups within
Q6. Read the following case study thoroughly and
answer the following questions:
Laxmi bank is one of the largest private sector banks
of India. It has an extensive network of more than 200 branches. It offers
banking services to retail as well as corporate clients. The bank faced a
challenge in integrating multi-pronged database management system into a
centralized system. The IT department of the bank also realized that the
computing capabilities of its PCs and servers were not proportionately
distributed among all its branches. Each branch had its database management
system stored in a traditional way on the disk. The total cost of operating and
maintaining the current IT infrastructure was very high and the fundamental
shortcomings added to the costs. Moreover, there were also recurrent problems
due to the malfunctioning of the currently operational database management
system. Therefore, the bank’s top management decided to fix the problem and
operationalise a robust database management system. The bank hired an external
database technology consulting firm called AKPY Info systems Limited.
AKPY divided the entire IT infrastructure of the bank
around two verticals. The retail banking vertical and the corporate banking
vertical. All the individual database servers from the individual branches were
removed. The entire database system was made virtual such that the managers and
the staff can access only the required information (related to retail banking
or corporate banking) from the respective centralized data centers. There were
only two such centralized data centers (one for retail banking and another for
corporate banking) that were managed centrally. Staff and managers could access
the information through their PCs and laptops. Centralized database management system
complemented the security system by
bringing in authentication through a unified ID management server.
Managers and officers of the bank were able to process half a million
transactions per month in real time after the new implementation. There were
significant savings in the cost and also in the consumption of power. Now there
were no problems with regard to imbalances in the load across various network
servers. Due to centralized data management, top management could keep an eye
on the functioning of various branches. Hence the cases of fraud and cheating
reduced considerably. The bank managers could also process the loan
applications in reduced time since the customer’s previous records could be
accessed at the click of the button and approval from the higher authorities
could be obtained in real time. Moreover the new system also brought in many
applications that helped local managers in the decision making process.
a. List the uses of centralized data management
b. What steps Laxmi bank need to take if it were to
change its centralised database system to a distributed database system in
future?
(a. Listing the uses from the from the case study-2
marks, b. Explaining about data fragmentation, replication and allocation
techniques-6 marks, c. Is it possible to replicate the centralised database
management model of the bank-2 marks) 10 marks
Answer. Answer.
a) Uses of centralized data management
A centralized database is a database located and maintained in one
location, unlike a distributed database. One main advantage is that all data is
located in one place. A centralized data management system can be use as:
1.
The Two such centralized data centers (one for retail banking
and another for corporate banking) that were managed centraly. Staff and
managers could
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