Transcript IMS1907 Database Systems

IMS1907 Database Systems
Week 2
Types of Database Systems
Impact of Database Systems
The amount of information being collected and stored is
almost beyond comprehension – and its growing
Stored information is being used for more purposes than
were conceivable ten (or even five) years ago
Databases are used at every level of society
– individuals, small business, national organisations, global
corporations, governments…
They affect many aspects of our everyday lives
Monash University 2004
2
Impact of Database Systems
Databases are used in
– monitoring and improving business operations
– tracking customers and their behaviour
– tracking and despatching emergency service vehicles
– monitoring communications with space vehicles
– making decisions (business and otherwise)
– generating spam
– performing surgical procedures
– many other applications from the mundane to miraculous
Monash University 2004
3
Impact of Database Systems
Critical to business productivity and profitability
Critical to individual life and safety
Instrumental in economic and social stability
Can affect governments
It essential that information is accurate, up-to-date and
consistent
Not always easy when there are so many databases of so
many types storing different versions of similar or the same
information
Monash University 2004
4
A Brief History of Database Systems
3000BC(?)
knotted and coloured string, marks on clay
2000BC(?)
papyrus-based recording
200BC(?)
paper-based technologies
1950
file processing systems
1970
hierarchical DBMS,network DBMS (first
generation DBMS), Codd’s relational
model
Monash University 2004
5
A Brief History of Database Systems
1980
1990
2000+
relational DBMS (second generation
DBMS), SQL
internet, data warehouses, object-oriented
DBMS, distributed databases
more complex data structures, universal
servers, centralised databases, contentaddressable storage, AI, data mining,
mobile technologies, super computers…
Monash University 2004
6
Types of Database Systems
Personal Databases
Workgroup Databases
Department Databases
Enterprise Databases
Internet, Intranet, and Extranet Databases
Data warehouses
Monash University 2004
7
Personal Databases
Support single user
PCs, laptops, personal digital assistants (PDA), mobile
phones…
Improve personal productivity
Can be difficult to share data of interest to other users
Used in small organisations when need to share data is
unlikely
MS Access, Oracle Personal, FoxPro…
Monash University 2004
8
Personal Databases
Considerations for developing personal databases include
– develop in-house vs outside vendor
– developed by end user or IT staff
– data requirements, database design requirements
– which commercial DBMS?
– can data be synchronised with other databases? How?
– who is responsible for data in personal database?
Monash University 2004
9
Workgroup Databases
Workgroups – small teams (typically less than 25 people)
collaborating on the same project or application or group of
similar projects or applications
Workgroup database
– supports collaborative effort
– allows change tracking, ease of data sharing
– allows concurrent user updating
Typically stored on database server and provided to users
via a Local Area Network (LAN)
Monash University 2004
10
Workgroup Databases
Considerations for developing workgroup databases include
– data management issues - data security, data integrity
– multiple user views, multiple subscribing to databases
– database design optimisation for and between different
group members
– how can concurrent access needs be met without
compromising data integrity?
– where should processing take place – client vs server?
Monash University 2004
11
Department Databases
Support functional units of an organisation
– sales, personnel, marketing, manufacturing, accounting
Contain data necessary
– to perform functions and processes within specific activity
area
– to answer questions relevant to specific activity area
Large numbers of users often in geographically dispersed
locations
Possibly the most common type of database
Monash University 2004
12
Department Databases
Considerations for developing department databases
include
– design of DB and environment for adequate performance
with large number of users and user transactions
– security protecting against unauthorised access to or
distribution of sensitive data
– which DB and application development tools are
appropriate for complex environment?
Monash University 2004
13
Department Databases
Considerations for developing department databases
include
– does similar data exist elsewhere in organisation? How
can we manage redundancy, consistency, metadata?
– is a distributed database system needed? Are users
geographically dispersed? Does size of DB require
storage on several systems?
– should database be web-enabled? Incorporated in
intranet environment?
Monash University 2004
14
Enterprise Databases
Scope covers an entire organisation (or at least many
different departments!)
Support organisation-wide operations, decision making
Organisation may have several enterprise databases
– enterprise DB not truly inclusive of all organisational data
– single operational DB may be impractical due to
performance difficulties, diverse needs, metadata
definition problems
Enterprise Resource Planning (ERP) systems, data
warehouses
Monash University 2004
15
Enterprise Databases
Considerations for developing enterprise databases include
– how should data be distributed throughout the various
locations in the organisation?
– how can standards be developed and maintained
throughout the organisation for data names, definitions,
formats and related issues?
– what do we need to do to ensure successful integration of
numerous data sources including legacy systems?
Monash University 2004
16
Internet, Intranet and Extranet Databases
The proliferation of the Internet has been one of the most
significant drivers of technological and business change
– highly competitive
– improved customer information
– eliminate traditional marketing/distribution channels
– employee relationship management
– direct sales
– ticket booking
– e-auctions, share trades
Monash University 2004
17
Internet, Intranet and Extranet Databases
Need for database support, universal data access
Internet provides easy connection across multiple platforms
Browser-based applications utilise standard interface – lower
development costs
Web-enabled databases allow users to ask unique and
specific questions and receive answers based on current
information
Online shopping, airline ticket booking, auctions
These are mostly BC (business-to-consumer)
Monash University 2004
18
Internet, Intranet and Extranet Databases
Businesses also deal with other businesses BB
Traditionally they used electronic data interchange (EDI) as
a means to trade information
Extranets are internet-enabled but access is not universal
– utilise XML to provide standard format
They allow businesses to gain limited access to and use of
each others information
Fosters relationships via more efficient exchanges
Often gives access to part of company intranet
Monash University 2004
19
Internet, Intranet and Extranet Databases
Businesses often use internet technology to create internal
private networks – intranets
Allow exchange and management of information within an
organisation
– HR, financial, programs, training, news…
Only internal access to data is allowed
Can be used to connect to internet
Requires additional technology to restrict external access
Monash University 2004
20
Internet, Intranet and Extranet Databases
Considerations for developing web-enabled databases
include
– the type of technology used to link web applications to
client databases (middleware, protocols…)
– the measures and technology necessary to ensure
security and privacy (firewalls, passwords, encryption…)
– the staggering amount of data generated via the internet
– maintenance of data quality in environment where data
sources are external
Monash University 2004
21
Types of Database Users
Naïve users
– unsophisticated
– interact via application programs
– fill in forms, view reports
Application programmers
– usually computer professionals
– use methodologies, tools, languages (3GL, 4GL) to
create interfaces
Monash University 2004
22
Types of Database Users
Sophisticated users
– interact with DBMS without program interface
– use database query language via a query processor
– use online analytical processing tools, data mining tools
Specialised users
– who write specialised programs outside traditional DBMS
– computer-aided design (CAD) systems, knowledgebased systems (KBS), expert systems, complex data
type storage systems, environment-modelling systems
Monash University 2004
23
References
Elmasri, R. and Navathe, S.B., (2000), Fundamentals of Database
Systems, (3rd edn.), Addison-Wesley, Reading, Massachusetts,
USA.
Hoffer, J.A., Prescott, M.B. and McFadden, F.R., (2002), Modern
Database Management, (7th edn.), Pearson Education Inc.,
Upper Saddle River, NJ, USA.
Murphy, B., (1999), Data Downtime Dilemma, accessed 5th July
2004 at
http://www.findarticles.com/p/articles/mi_m0SMG/is_3_19/ai_593
29322.
Silberschatz, A., Korth, H.F. and Sudarshan, S., (2002), Database
System Concepts, (4th edn.), McGraw-Hill Companies Inc.,
Boston, Mass., USA.
Monash University 2004
24