ASSESSEMENT and ASSIGNMENT BRIEF

ASSESSEMENT and ASSIGNMENT BRIEF

Unit 17 : Database Design Concepts UNIT CODE: R/601/0447Learning Hours: 45 Hours S elf-learning hours: 90 hoursCourse: HND CSD – Level 4 Credits: 15Term: Lecturer: Mohammed Hasan Verifier:

Learners Name Sarmila SriharanRegistration Number HNDCSD9816Learners Declaration: I certify that the work submitted for this unit is my own:Signed:Hand out Date: 30/09/2013 Submission Date: 18/01/14The Following Sections to be completed by the assessor:Center Name: UKCBCCenter Number: Please note that the assessors signature below denotes conformation that he/she has in no way influenced the outcome of the assessment: Assessors Name:Assessors Signature:

Has the unit been Internally Verified? Y/NDate of verification:Internal verifiers signature:Internal verifiers assignment brief:

Sarmila Sriharani, Batch-2

Task No. Description PageNo.

Task - 1 P1.1 Analyse the Key Issues and Application of Databases withinOrganisational Environments

03

P1.2 Critically Evaluate the Features and Advantages ofDatabase Management Systems

7

Task - 2 P2.1- Analyse a Database Developmental Methodology 12

P2.2- Discuss Entity-Relationship Modelling and Normalisation 17


LO1 UNDERSTAND DATABASES AND DATA MANAGEMENT SYSTEMS

P1.1 Analyse the Key Issues And Application Of Databases Within

Organisational Environments

DATABASE MANAGEMENT SYSTEMS (DBMS)

A database is a collection of related information and storing for

future purpose. Database Management is an important aspect of data

processing. It involves, several data models evolving into different

DBMS software packages. Some commercially available DBMS are INGRES,

ORACLE, and Sybase.

ADVANTAGES OF DBMS

Data were processed using file processing system before DBMS

1. User is not required to write the procedures for managing the

database.

2. It provides an abstract view of data that hides the details.

3. It is efficient to use

4. It takes care of Concurrent access using some form of locking.

5. It has crash recovery mechanism

6. It has a good protection mechanism if the system fails.

(elearning.vtu.ac.in)

KEY ISSUES OF DBMS:

The key issues of DBMS such as:

(ijarcce.com, Vol. 2, Issue 7, July 2013)

1. Centralised Control

In DBMS all the data of the organization is joined into the

single database. This database is under the control of a

central database management system (DBMS) in which storage

devices are not all attached to a Common Central Processing


unit (CPU). It may be stored in multiple computers located in

the same physical location, or may be dispersed over a network

of interconnected computers.

2. Data redundancy

Data redundancy means duplication of data. Database are

created in the system, the same data may have to be recorded

and stored in many files. So in that case the repetition of

information about an entity cannot be avoided.

(elearning.ukcbc.co.uk, Further Reading DBMS PDF)

For Example: personal file and payroll file, both contain data

on employee name, designation etc.

DBMS avoids unnecessary duplication of data and effectively

reduces the total amount of data storage required.

3. Sharing Data

This allows the user could share data like any number of

application programs under its control. That means accessing

the data by multiple users at same time.

4. Concurrency Problems

When more than one user is allowed to process the database and if in

that case two or more users try to update a shared data element at

about the same time then it may result into inconsistent data.

(ijarcce.com, Vol. 2, Issue 7, July 2013)

5. Backup and Recovery

It provides recovery and backup from the failures like disk crash,

power failure etc which help to recover the database from

inconsistent state.


ACID TRANSACTIONS:

An ACID transaction is a sequence of database operations that has the following properties:

1. A tomicity

Any hardware or power failure, during the transaction is not

able to complete the process and its going back to the

starting level of transaction. ( msdn.microsoft.com)

2. C onsistency

At the end of any consistency, the DBM systems will confirming

that it is in a valid state.

For Example: A transaction maps a correct database state to

another correct state

3. Data Isolation

Many simultaneous transactions could happen without disturbingeach other.

4. D urability

: After the transaction has been successfully completed; all

of the changes it made to the system are permanent

(elearning.ukcbc.co.uk,ACID Properties file)


APPLICATION AREAS OF DATABASE SYSTEMDatabase systems are widely used in different areas because of their

various advantages. Some of the most common database applications

are listed here.

(safaribooksonline.com/book/databases)

1. Banking

Banks use databases for customer inquiry, accounts, loans, and

other transactions. The database is well designed and its

control all the branches customer transaction and other

operations. The bank data has been normalised by their

customer details for required query.

For example: The clients make deposits and withdrawals from a

local branch cash machine, this deposits are checked locally

and balanced and transactions from each branch are transmitted

to a headquarters or regional location for processing by DBMS.

(safaribooksonline.com/book/databases)

2. Education

In education department has the centralised DBM system for all

their purposes. Schools and colleges use databases for course

registration, result, and other information. The DBM systems

are used to manage student and staff information across all

areas of school life including registration, finance (fees)

and payroll, timetabling, progress tracking and assessment,

and whole-school communication in the form of e-mails or chat.

This DBMS helps them to access and maintaing the details quick

and safely. (safaribooksonline.com/book/databases)

3. Hospital

In hospital the databases are used for maintaining the patient

health care details, doctor’s details, appointments and salary


details of the employees. The database helps them to give good

service to the patients and others.

4. E-commerce

Online sales have a huge development in recent years. The

databases are used to store product, customer and transaction

details. Moreover, databases are used for keeping track of

online payment and purchases on credit cards in order to

generate monthly statements (techterms.com)


Human Resources

The HR department use databases for storing information about

their employees, salaries, benefits, taxes, and for generating

salary checks. (safaribooksonline.com/book/databases)


P1.2 CRITICALLY EVALUATE THE FEATURES AND ADVANTAGES OF DATABASE MANAGEMENT SYSTEMS

FEATURES OF DBMS

(elearning.ukcbc.co.uk, Features of DBMS PDF) A good DBMS will havesome features to deliver good services, such as

1. Tools for the Administration

a) Remote Control

b) Operating tool Control

c) Lo2.1ading tool Load

d) Administration tool

e) Domain

2. Tools for the Microsoft Windows environment

a) ODBC driver

3. Tools for the Internet / Intranet

a) Perl interface

b) JDBC driver

c) Open interfaces

d) GUI Query

e) Programming tool SQL-PL

f) CALL interface (ODBC on UNIX and Linux)

g) Pre-compilers

h) TCL/TK interface

Let’s see some of the above features of DBMS

1. Remote Control

Remote access is access between an organizational information

system and a user communicating through an external, non-

organization controlled network (e.g., the Internet).


Remote Control supports remote administration of many database

servers providing a convenient graphical interface. Also it

supports the important tasks such as starting and stopping,

monitoring, backup, recovery and complex tasks can be

performed with Control. (elearning.ukcbc.co.uk, Features of

DBMS PDF)

2. Overview of Open Database Connectivity (ODBC) Driver

ODBC is an industry standard application program interface

(API) that provides a solution to a common problem.

A driver is a dynamic link library (DLL) that implements ODBC

function calls and interacts with a data source. The ODBC

driver allows database to be accessed from any Windows tools

with an ODBC interface

For Example: Access, Excel, MS Query, Visual Basic,

PowerBuilder, SQL and Windows). (elearning.ukcbc.co.uk,

Features of DBMS PDF)

3. GUI Query

GUI Query provides a Graphical User Interface (GUI) for

creating SQL queries. This includes a pane that displays user

query graphically and text versions, so user can click and

drag while also seeing the results in SQL. The GUI Query can

be used to enter SQL statements interactively and to access

the database catalogue. There is the possibility to access the

SQL Online Tutorial from.

GUI Query to perform the following tasks:

i. Working with a graphical representation of a query or

with SQL


ii. Joining related tables -user could add more than one

table to their query, it determines how the tables are

related and constructs the appropriate join command.

iii. Querying or updating databases - user can use GUI Query

to return data by using Transact-SQL SELECT statements

and to create queries that update, add, or delete records

in a database.

iv. Viewing and editing results

immediately(elearning.ukcbc.co.uk, Features of DBMS PDF)

4. Perl-Interface

The Perl interface allows database to be accessed from the

script language Perl using the DBI access standard. In this

way, complex Web applications can be developed.

5. SQL-PL

SQL-PL is the language to use when writing code that resides

in the database. Another feature of PL/SQL is that it allows

user to store compiled code directly in the database. This

supports any number of applications or users to share the same

functions and procedures. This can be used to create DB

procedures, triggers, and DB functions out of the development


environment, and to test and operate them on both the client

server.

6. Trigger

The definition of the SQL trigger is stored in the database

management system and is invoked by the database management

system, when the SQL table, that the trigger is defined on, is

modified. The trigger resides in the database and lets the

user to write a set of SQL statements that multiple

applications can use. It lets the user to avoid redundant code

when multiple programs need to perform the same database

operation. The triggers are activated indirectly by means of

the SQL statements INSERT, UPDATE, and DELETE.

(publib.boulder.ibm.com)

Triggers are commonly used to:

a) Audit changes

b) Improve changes

c) Enforce and excute business rules

d) Reproducing data

e) Enhance performance

ADVANTAGES OF DBMS1. Reduction of Redundancies

Data redundancy means duplication of data. DBMS avoids

unnecessary duplication of data and effectively reduces the

total amount of data storage required. It is also eliminates

the extra processing to trace the required data in a large

mass of data.


Any redundancies that exist in the DBMS are controlled and the

system ensures that these multiple copies are stable.

(elearning.ukcbc.co.uk, Further Reading DBMS PDF)

2. Data integrity

This means that the stored values in the data base should be

accurate and must satisfy some rules. Therefore, data values

being entered for storage could be checked to ensure that they

stored within a specified range and correct format. Apply

various types of constraints like Primary Key, Foreign Key,

Unique, NOT NULL, Check for data integrity.

For example, the value for the age of an employee may be in the

range of 16 and 75.

3. Conflict Resolution:

DBMS has the best file structure and access method to get best

performance for the response-critical applications, while

permitting less critical applications to continue to use die

database, albeit with a relatively slower response.

4. Data Independence

Data independence is a form of database management that keeps

data separated from all programs that make use of it. In DBMS

or database management system, this independence ensures that

the data cannot be redefined or reorganized by any of the

programs that make use of it. In this manner, the data remains

accessible, but it is also stable and cannot be corrupted by

the applications.

5. Security And Access Control

Database should be protected from unauthorized users. Every

user should not be allowed to access every data. Since


application programs are added to the system For example: The

Payroll Personnel in a bank should not be allowed to access

accounts information of the customers. (elearning.ukcbc.co.uk,

Further Reading DBMS PDF)

6. Data Availability

Data availability means that data continues to be available at

a required level of performance. Basically, the data

availability is achieved through redundancy involving where

the data is stored and how it can be reached.

Data is one of the most critical business assets of an

organization. If this data is not available and/or not

protected, companies may stand to lose millions of dollars in

business downtime as well as negative publicity.

(elearning.ukcbc,Further Reading DBMS PDF)

Availability comprises four distinct components, such as

a) Manageability - Create and maintain an effective environment

that delivers service to users

b) Recoverability — Rebuild service skills if the system failure

c) Reliability - Supply good service at specified levels for a

stated period

d) Serviceability — the ability to determine the existence of

problems, analyse their cause(s), and repair the problems

All four of these impact the overall availability of a system,

database, or application.


LO2 UNDERSTAND DATABASE DESIGN TECHNIQUES

P2.1- ANALYSE A DATABASE DEVELOPMENTAL METHODOLOGY SUCH AS SSADM AND ITS

PHASES FEASIBILITY STUDY, REQUIREMENT ANALYSIS, REQUIREMENT SPECIFICATION,

PHYSICAL DESIGN ETC.

DATABASE DEVELOPMENT

When designing a database the following properties are important for

a good design and implementation of the Database

a) Completeness - Ensure that users can access the data they want

and any time or any place

b) Integrity - Ensures that data is both consistent and correct that

means no invalid data

c) Flexibility - Ensures that a database without requiring a lot of

effort to satisfy changing requirements

d) Efficiency - Good Response Time

e) Usability - Database must be easy to use

SSADM STRUCTURED SYSTEMS ANALYSIS AND DESIGN METHODOLOGY

SSADM is an analysis and design methodology. There is no

implementation, maintenance, testing and review of the Conventional

Approach. This makes use of phases (stages) and sub-phases, all

exactly detailed. This allows project management tools to be used

alongside the methodology.( elearning.ukcbc.co.uk, Further Reading

SSADM PDF)

IMPORTANT CHARACTERISTICS OF SSADM

a) Dividing a project into small modules with well defined

objectives

b) Useful during requirements specification and system design

stage


c) Diagrammatic representation and other useful modelling

techniques

d) Simple and easily understood by clients and developers

e) Performing activities in a sequence

KEY BENEFITS OF SSADM

a) Teachable

b) Effective use of both experienced and inexperienced staff

c) Great resilience against loss of key staff

d) Improved involvement of end user over Conventional Approach

e) Earlier/better validation of stages of analysis and design

f) More complete and less ambiguous specifications

g) More maintainable systems

h) Improved management control of systems development

DISADVANTAGES OF SSADM

a) Causes the danger of over-analysing

b) It can be very time and cost consuming

c) With large systems, the outline diagram can become very

unclear, because all relevant data flows have to be included.

It recognises the following stages in the systems development

lifecycle.


1. Feasibility

In this stage involves a high level analysis of business area to

fix the cost and technical effective systems. Moreover, it is

concerned about the project in planning is feasible to all the

possible ways like scope, requirements and compare with current

options to various alternatives. Systems investigation

techniques, such as collect information by contacting interviews

of people at all levels of the organization; analyse

questionnaires; review short and long term plans, business

manuals, files, forms, etc. and their data flow diagrams. Entity

models are drawn, but only in outline and in not too great

detail.

This phase has 4 steps:

a) Prepare for the study- plan all possible way to develop a

project

b) The scope of the project- analyse the requirements and scope

of the project

c) Define the problem- identify the problems

d) Compares requirements with current position- consider the

various alternatives and recommend the best option from both

the business and technical point of view for the project

All this information is then published in the feasibility report.

2. Requirements Analysis

This stage investigates of current requirements and business

system options. One of these options will be chosen then refined

in the later stages.

Current requirements


a) The feasibility stage is carried out very much in outline

and the investigation of current environment may have much

less of a basis for the tasks at this stage.

b) In this stage the new system are examined along with

investigating the current processing methods and data of the

current system.

c) Physical Data Flow Modelling and Logical Data Modelling can

be used as technique during this stage.

d) Catalogues will be created, such as the user catalogue,

which lists the activities carried out in each job, and the

requirements catalogue, which lists the functional and non-

functional requirements.


Business system options

The Business Systems Options, or BSO, stage allows the analyst to

choose between a numbers of business-system options that each

describe the scope and functionality provided by a particular

development and implementation approach.

If the business system options are satisfying the requirements,

and a few of these are presented to management so that one can be

chosen. This include outline of the cost, development time scale,

technical constraints, physical organisation, volumes, training

requirements, benefits and impacts on the organisation. The

chosen option documented in detail and agreed as the basis of the

system specification which is the next stage.

A data flow diagram’s (DFD) and Entity–relationship model‘s are

developed but this stage is largely a specification in narrative.

3. Requirements Specification

This provides clear guidance to the design stages where

investigation and analysis are replaced by specification and

design. The requirements catalogue will be analysed and updated

for the better design. Data Flow Modelling, Logical Data

Modelling, Entity Event Modelling and normalisation can be used

as technique during this stage.

The inputs, outputs and events or enquiry triggers for each

function are defined and documented in detail usually on forms

which give function name, description, error handling, data flow

diagram processes, events and input and output descriptions. At

the end of this stage the system objectives, the functions are

checked and verified for the completeness of definition and the

full requirements specification documented.


4. Logical System Specifications

This specification has two stages such as:

a) Technical System Options

This stage result is the technical selected and detailed

option. In this stage the system environment such as

hardware and software configure, development strategy,

organisational impact and system functionality are

determined by the analysts. This stage is a really rely on

development or implementation specific, because there are so

many alternative hardware, software and implementation

strategies.

Hence this stage allows the analyst to consider the

technical options and etails such as the terms of cost,

performance and impact on the organisation is determined.

The analyst should identify, define and select the possible

technical system option in this stage.

b) Logical Design

In this stage a detailed logical pattern mainly containing

the data and the procedures plan is explained.

(www.sqa.org.uk/e-learning)

a) The data plan is made by using the normalization

entities data base technique.

b) The procedures plan is made by enlarging several

detailed processes outlines.

c) The data and the procedures plans are made

simultaneously.

d) User involvement is recommended at this stage and

samples which are developed in stage 3 will be

referred to current. Moreover, the further detail


about how the system will apply, control operations

following each event and the rules of validating data

entered into the system will be defined or specified

in this stage.

5. Physical Design

This is the final stage of SSADM and provides guidelines

regarding physical implementation which should be applicable to

most hardware and software configurations. During this design the

logical system specification and technical specification are used

to create a physical design and a set program specifications. The

detailed logical project is converted into a technical project

with the well suited equipment’s and software. . It includes data

about the files, the data base, the integrated programs, the

functions and the used procedures. In the end of this stage the

development program and the test plans of the achieved system are

made, then the operation instructions and the manual procedures

are specified and the detailed specifications of the program

(elearning.ukcbc.co.uk, Further Reading SSADM PDF)

P2.2 - DISCUSS ENTITY-RELATIONSHIP MODELING SUCH AS ONE-TO-ONE, ONE-

TO-MANY AND MANY-TO-MANY RELATIONSHIP AND NORMALIZATION WITH 1ST,

2ND AND 3RD NORMALIZATION TO DESIGN DATABASE SOLUTION FOR COMPUTER

CHOICE.


DATA MODELING

Data modeling is the formalization and documentation of existing

processes and events that occur during application software design

and development. Data modelers often use multiple models to view the

same data and ensure that all processes, entities, relationships and

data flows have been identified.

ENTITY-RELATIONSHIP Diagram

This is a data modeling technique and a graphical representation of

the entities and the relationships between them. Entity relationship

diagrams are a useful. (Margaret Rouse (March 2007),

searchcrm.techtarget.com)

The steps involved in creating an ERD are:

Identify the entities.

Determine all significant interactions.

Analyze the nature of the interactions.

raw the ERD

2. Components of E_R Diagram

a) Entity:

Entities represent objects or things of interest. In E-R

diagram it’s represented by rectangle.

For Example: in an organisation employee, department, product

and manager are entity.

b) Attributes

It describes the characteristic or property of an entity. An

attributes is represented by eclipse.


For Example: name, id, age and address can be attributes of the

student

c) Key attribute

It represents the main characteristic of an entity. It is used

to represent primary key and eclipse with underlying line

represent this.

d) Primary Key

A candidate key that is chosen to represent a record uniquely

called primary key. That is, a table may consist of many

candidate keys, but ONLY ONE can be selected as a primary key.

(sqa.org.uk)

e) Foreign Key

An attribute or a set of attributes of one table that is

matched to candidate keys of another table (or even the same

table)

a) One-to-One (1:1)Each entity in A can be related to at most one entity in

B, and vies versa

The above example describes that one student can enrol

any one course and course will also have only one

student.

b) One-to-Many (1: N)


Each entity in B can be related to at most one entity in

A, but an entity in A may be related to many entities in

B.

For Example: student enrols only one course but course can

have many students

c) Many-to-Many (N:N)

An entity can be related to many entities in the other

set, and vice versa

The above figure represents that many students can enrol

for more than one course (Studytonight 2013)

NORMALIZATION OF DATABASE

This is a systematic way of decomposing tables to eliminate data

redundancy and undesirable characteristics like insertion, update

and deletion anomalies (Studytonight 2013)

Normalizations could be divided into three forms

1. First Normal form

The following requirements should to satisfy the 1st NF:

No multivalued attributes

Every attribute value is atomic


There are no repeating groups: two columns do not store

similar information in the same table.

Table-1

The above table have multiple values and reducing

duplicate or multi value entries in the first for then

the table would look like:

2. 2nd Normal Form

The requirements to satisfy the 2nd NF:

All requirements for 1st NF must be met.

Each table has a primary key: minimal set of attributes

which can uniquely identify a record

Every non-key attribute must be defined by the entire

key, not by only part of the key

No partial functional dependencies


Redundant data across multiple rows of a table must be

moved to a separate table.

The resulting tables must be related to each other by use

of foreign key.

For Example: the product datails will look like:

3. 3rd Normal Form

The requirements to satisfy the 3rd NF:

All requirements for 2nd NF must be met.

Eliminate fields that do not depend on the primary key;

that is, any field that is dependent not only on the

primary key but also on another field must be moved to

another table. This is called transitive

Normalization can decrease redundancy, increase efficiency and

reduce anomalies by implementing three levels of normalization

called Normal Forms. The three NF’s are usually sufficient for most

small to medium size applications. (cse.yeditepe.edu.tr)


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