HND Agri
DBMS
Introduction
MH Mohamed Nafas
1
Why DBMS?
Suppose we need to develop a Information system.
How do we


store the data? (use file structures…)
 query the data? (write programs…)
 Update data safely? (write more programs…)
 provide different views on the same data?

(staff & students diffrent) ( prog…)

deal with crashes? (prog…)
DBMS helps to above activities.

2
File based system
Manual file Processing (paper based)

Time Consuming
 Does not support large volumes of data


File based Processing

Database Management system
3
ID
File Based Processing
Name
Data
Entry
File
Processing
Address
TelNo
001
mery
colombo
747374
Marks
34
Student System Files
ID
Name
Address
TelNo
Data
Entry
4
File
Processing
Data Duplication
Books-bor
001
mery
colombo
747374
6
Library System Files
ID
File Based Processing
Name
Change request
Data
Entry
File
Processing
Address
TelNo
001
mery
colombo
747374
Marks
34
Student System Files
ID
Name
Address
TelNo
Data
Entry
File
Processing
Books-bor
001
mery
colombo
747374
6
Library System Files
5
ID
File Based Processing
Name
Address Change request
Data
Entry
File
Processing
001
mery
Address
Kandy
TelNo
747374
Marks
34
Student System Files
ID
Name
Address
TelNo
Data
Entry
6
File
Processing
Inconsistent Data
Books-bor
001
mery
colombo
747374
6
Library System Files
Problem in file based system

Inconsistent data
Data duplication
Security
Inflexibility
Limited data sharing
Excessive program maintenance

How do we resolve these problems?





7
Solution is DBMS
DBMS is solution to rectify file based processing
problems

8
Database Processing
Change Request
Data Entry &
Reports
Students
stno
Name
001
mery
…………….
address
colombo
Application
Programs
DBMS
Data Entry &
Reports
Library
App. Programs
Database
Database Processing
Change Request
Data Entry &
Reports
Students
stno
001
…………….
Name
mery
address
Kandy
Application
Programs
DBMS
Data Entry &
Reports
Library
App. Programs
Database
DATABASE
DEFINITION

A shared collection of logically related data designed to
meet the information requirements of an organisation.
11
Database Management System (DBMS)

A software system that enables users to define, create
and maintain the database and which provides controlled
access to the database.
12
History of Database Systems

1950s and early 1960s:

Data processing using magnetic tapes for storage



Tapes provide only sequential access
Punched cards for input
Late 1960s and 1970s:



Hard disks allow direct access to data
Network and hierarchical data models in widespread use
Ted Codd defines the relational data model




13
Would win the ACM Turing Award for this work
IBM Research begins System R prototype
UC Berkeley begins Ingres prototype
High-performance (for the era) transaction processing
History (cont.)
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1980s:
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Research relational prototypes evolve into commercial systems
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Parallel and distributed database systems
Object-oriented database systems
1990s:
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SQL becomes industry standard
Large decision support and data-mining applications
Large multi-terabyte data warehouses
Emergence of Web commerce
2000s:
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14
XML and XQuery standards
Automated database administration
Increasing use of highly parallel database systems
Web-scale distributed data storage systems
Database models
Early Types of DBMS
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Hierarchical

Network
Current Generation

Relational
Advanced Systems
-
15
Object Based
What is a Database System?
Database System = Database + DBMS

A Database is


A large, integrated collection of data
Models (represents) a real-world enterprise.
Entities (e.g., students, courses)
Relationships (e.g., Mary takes CS123)

A Database Management System (DBMS) is


A software package designed to store and
Manages databases easily and efficiently.
16
Common Uses of Databases

Try to think why each of these need to use a
database:
 Supermarkets
 Insurance
 Credit Cards/Banking
 Libraries
 Travel Agents
 Universities
17
Examples: DBMS
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MSAccess
MySQL – freeware (Windows & Unix)
McKoi – freeware, Java based.
Oracle
SQL Server – Microsoft product – we use in this course
Any other ?
Common features:
 Relational model
 SQL as query language
 Server-client architecture
18
Advantages of using a DBMS
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Minimal data redundancy
Efficient data access
Data integrity and security
Data administration
Concurrent access, recovery from crashes
Reduced application development time
19
Disadvantages





Complexity
Additional Hardware costs
Experts – Specialised personnel
Higher impact of failure
Simple applications may not need DBMS at all
20
Questions?
21