2. Lecture Outline
Disadvantages of DBMS.
Database Approach: Components &
Roles in Database Environment.
History of Databases
2
3. 3
The Database
A shared collection of logically related
data and its description, designed to
meet the information needs of an
organization
4. 4
(Database) Application Programs
Users interact with the database through a
number of application programs that are
used to create and maintain the database
and to generate information.
Sales and Contracts Departments using
their application programs to access the
database through the DBMS.
Each program handles data entry, data
maintenance, and the generation of report
6. 6
Views
DBMS provides another facility known
as a view mechanism, which allows
each user to have his or her own view.
View is a subset of databases
Views provide a level of security.
Views provide a mechanism to
customize the appearance of the
database.
7. 7
Components of the DBMS
Environment
We can identify five major components in
the DBMS environment:
Hardware
Software
Data
Procedures
People
9. 9
Software
The software component comprises the
DBMS software itself and the
application programs, together with the
operating system, including network
software if the DBMS is being used over
a network.
Written in query languages SQL, C++,
Java
10. 10
Data
Most important component of the DBMS
environment—certainly from the end-users’
point of view—is the data.
Acts as a bridge between the machine
components and the human components.
The database contains both the operational
data and the metadata, the “data about
data.”
The structure of the database is called the
schema.
11. 11
Procedures
Procedures refer to the instructions and rules that govern the
design and use of the database.
The users of the system and the staff who manage the database
require documented procedures on how to use or run the
system. These may consist of instructions on how to:
Log on to the DBMS.
Use a particular DBMS facility or application program.
Start and stop the DBMS.
Make backup copies of the database.
Handle hardware or software failures. This may include
procedures on how to identify the failed component, how to fix
the failed component
Change the structure of a table, reorganize the database
across multiple disks
12. 12
Roles in Database
environment
Data and Database Administrators
Database Designers
Logical database designer
Physical database designer
Application Developers
End-Users
13. 13
Types of Databases based on
location
Centralized database:
A database that supports data located at a
single site is called a centralized database
Distributed database:
A database that supports data distributed
across several different sites is called a
distributed database
14. 14
Centralized Database
If a database is located at a single location and different
users at different places access the database from that
single location, then it is known as Centralized Database.
16. 16
Distributed Databases
A distributed database is a single logical
database, which is spread physically across
multiple computers (called database servers)
over wide area network
Such databases are managed by the
organizations having offices in different cities or
countries
Any user at any office can access data of his
office as well as of other offices
18. 18
Distributed DataBase
+ Data access and retrieval faster at nearest points
- Can be slower accessing non local data
- Need to be ensure data is consistent / synchronised
19. 19
Distributed Database
Homogeneous Database
all nodes use the same hardware, software (OS & DBMS)
and data structures for the database system
Heterogeneous Database
different nodes may have different hardware & software
(OS & DBMS) and data structures at various nodes or
locations are also incompatible
20. 20
Databases Type based on
operation
Operational database:
A database that is designed primarily to support a company’s
day-to-day operations is classified as an operational database
aka Transactional or Production database
Data warehouse:
Integrated decision support system derived from various
operational databases on periodic basis
A data warehouse focuses primarily on storing data used to
generate information required to make tactical or strategic
decisions like to formulate pricing decisions, sales forecasts,
market positioning, and so on.
22. 22
Database Development
Two Approaches to Database
Development
SDLC
System Development Life Cycle
Traditional methodology used to develop, maintain, and
replace information systems
Detailed, well-planned development process
Time-consuming, but comprehensive
Long development cycle
23. 23
Prototyping
Rapid application development (RAD)
Cursory attempt at conceptual data modeling
Define database during development of initial prototype
Repeat implementation and maintenance activities with
new prototype versions
25. 25
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Purpose–preliminary understanding
Deliverable–request for study
Database activity–
enterprise modeling and early conceptual data modeling
26. 26
Disadvantages of DBMS
Complexity
Size
Cost of DBMSs
Additional hardware costs
Cost of conversion
Performance
Greater impact of a failure
27. 27
Discuss each of the following terms: (a)
data (b) database (c) database
management system (d) database
application program (e) data
independence (f)security (g) integrity (h)
views
28. 28
Interview some users of database
systems. Which DBMS features do they
find most useful and why? Which DBMS
facilities do they find least useful and
why? What do these users perceive to
be the advantages and disadvantages
of the DBMS?
Editor's Notes
#2: 2 Discuss each of the following terms: (a) data (b) database (c) database management system (d) database application program (e) data independence (f)security (g) integrity (h) views
