Database

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Áine Mitchell
– Computer Software Developer / Team Leader / Project manager
– Oracle Database Systems in different Organisations
– [email protected]
– Room - B1082
– Phone - 9155228
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Data Management
Introduction
2
Data Management
What is Database and its Purpose
What types of Data Company needs to
store
Data as a resource
DBMS – Features and Advantages
Functionality of DBMS
Issues with Data Management
Centralised Data Management
3
Traditional File Systems
All automated systems which use data must
store this data somewhere.
Traditionally this data was stored in files.
Each program or application had its own files in
its own format
It was difficult to integrate data from different
systems.
The data and the program were tightly coupled,
so if one changed the other had to change also.
– E.g. changing to 8 digit phone numbers.
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Purpose of Database
Businesses of every size organize data
records into collections called databases.
Small businesses for example use
databases to keep track of customers
Huge corporations such as Dell and
Amazon.com use databases to support
complex sales, marketing, and operations
activities
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Huge Quantities of Data
Modern systems produce huge amounts of
data.
– EPOS system.
– Web retail site
– Decision Support Systems
– ERP Systems– Enterprise Resource Planning
HR, Financials,Distribution,Product LifeCycle
Customer Relationship Management CRM
Supply Chain – Purchasing, Manufacturing, Distribution
Commercial Applications
Manufacturing
Engineering, bills of material,
scheduling, capacity, workflow management, quality
control, cost management, manufacturing process,
manufacturing projects, manufacturing flow
Supply chain management Order to
cash, inventory, order entry, purchasing, product
configurator, supply chain planning, supplier scheduling,
inspection of goods,
Financials Claim processing, commission calculation
Financials General ledger, cash management, accounts
payable, accounts receivable, fixed assets
Commercial Applications
Project management
Costing, billing, time and
expense, performance units, activity management
Human resources
Human resources, payroll,
training, time and attendance, roistering, benefits
Customer relationship management
Sales
and marketing, commissions, service, customer contact
and call center support
Data services
Various "self-service" interfaces for
customers, suppliers, and/or employees
Access control
Management of user privileges for
various processes
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Data Requirements ?
HSE
City and Guild of London Institute
Company that Manufactures Paper Product
Bórd Na Mona
Mulit- National Computer Company
College
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Physical and Logical Data
Logical View
– Is concerned with the nature of the data or
information
– Logical view of a record is a set of data items
filling the structure
Physical View
– Involves physical aspects of the storage and
presentation
– How the Data is store, e.g. Employee # char(6)
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Data as a Resource
Organisation need to collect and manage
data to ensure that it can be accessed and
used by people across the organisation.
– Handle transactions
– Legal reasons
– Analyse, understand and improve their
business.
– Possible to gain a competitive advantage
What Is the Purpose of a
Database?
Purpose: to keep track of things
If structure of a list is simple, i.e., one
theme, no need to use database
technology (video)
Form for Recording Multiple
Themes
Database Based System
Rather than storing data in file systems
store it in data bases which can be
accessed by a variety of applications.
There are rules describing what kind of
data is stored and how it can be accessed
and changed.
The data is independent of the
applications.
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Database
Database:
 A self-describing collection of integrated
records
 In databases,
 bytes are grouped into columns, such as Student
Number and Student Name. Columns are also
called fields.
 Columns or fields, in turn, are grouped into rows,
which are also called records.
Database
A Database is an organised collection of
related data.
There are lots and lots of different ways to
organise data
Ideal method to organise data would
combine complete flexibility with complete
control.
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Hierarchy of Data
Characters, Fields, and Records
Hierarchy of Data Elements
Database is collection of Table or Files
Components of a Database
Application System
Applications make database data more accessible and
useful.
Users employ a database application that consists of
forms, formatted reports, queries, and application
programs.
Database management system (DBMS) processes
database tables for applications.
DBMS
DataBase Management System
A Database with Software for the following:
– Database definition
Specify the content and structure.
–
–
–
–
–
–
Data entry and modification.
Data processing and report generation.
Provides an interface to user programs (e.g. SQL).
Security.
Recovery
Centralized Control over the Data
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DBMS Products





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DB2 (from IBM)
MySQL (a free, open source DBMS)
Oracle (from Oracle Corporation)
SQL Server (from Microsoft)
ASE (from Sybase Corporation)
Access (from Microsoft)
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Advantages of using a DBMS
Separates the data from the programmes
using the data.
Reduces data redundancy and
inconsistency.
Reduces costs of developing new
applications.
Improves the flexibility of the information
systems
Security can be improved
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Desired functionality in a DBMS
What do you want from your data
management system?
– Database Definition
– Data Access
– Data Management
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Database Definition
Need to be able to define the database
structure and the contents.
What records can be stored.
What fields there are.
What the relationship between the records is.
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Data Access
Inserting new data
Searching for data
Generating reports
Updating data already stored.
Deleting data.
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Data Access
Speed of Access
Depending on the application the database may
be organised so updating is quick or so that
searching is quick.
Data may be indexed to allow speedy access.
Security of Access
Need to ensure that access to data is limited to
authorised users only.
May have different access levels so users can
search but not insert data etc.
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Issues in Data Management
Concurrency:
– Allowing multiple users to work on the database
simultaneously.
Not necessary in a single user system.
Transactions
– Allowing multiple records to be changed
instantaneously
e.g. transfer of funds between two accounts.
– Need to ensure that if there is a problem during the
transaction the database reverts to the original state
and that no one else can interfere with any of the
records during the transaction.
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Issues in Data Management
continued
Recovery
– Surviving application and system crashes
Copying of data.
– Ideally the database system should be able to import
data from other sources, and to export it for use
elsewhere.
– Need some way to back up databases and to restore
in the event of a system failure that damages the
database.
– hot backups is the term used when users can back up
databases while they are in use.
Needed for applications which must run without interruption,
and cannot be shut down for backups.
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Defining the database structure
The choice of DBMS will influence how the
data is organised.
It is important when defining the database
structure that the current and possible
future needs of the organisation are taken
into account.
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Centralised Data Management
Organisations may have data stored by different
applications.
– E.g. college may have student data in many different
locations.
Problems can still arise if there is no single
standard format for data.
– Cannot integrate the data from different databases.
Examples
– Field names may be different.
– Field contents may be different.
– Fields may be missing.
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Centralised Data Management
May be appropriate to have a single
company wide data standard.
– However there can also be problems with this.
It can be very difficult to agree on the
single standard.
Can lead to bureaucracy and lack of
flexibility.
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Conclusion
Keeping data in databases is better than
keeping it in file systems.
Data needs be managed.
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