26-05-2012, 05:35 PM
Database Management Systems
Database Management Systems.pptx (Size: 107.12 KB / Downloads: 28)
Database System
A very large integrated collection of data of the entities and relationships
Database system tries to model the real world systems and the underlying hierarchies, data (information)flows etc.
A Database Management System (DBMS) is a
software package designed to store and
manage databases.
Why Study Databases?
Many computing applications deal with large amounts of information
Database systems give a set of tools for storing, searching and managing this information
Databases are a ‘core topic’ in computer science
Basic concepts and skills with database systems will help Engineers to deal with many computerized information systems, CAD tools, GIS, etc
Informatics
Study of database systems has graduated as a major field of specialization namely Informatics
Eg. Bioinformatics
Data and Database
A database is a collection of related data
By data we mean known facts that can be recorded and that have implicit meaning
Eg. The name of a person becomes data for the Institute if he/she is a student or employee or supplier or examiner or some of that kind of relation exists
Database
A database has many implicit properties
A database represents some aspects of the real world sometimes called the mini world or the Universe of Discourse(UoD)
Changes to the mini world are reflected in the database
Properties of database
2. A database is a logically coherent collection of data with some inherent meaning. A random assortment of data cannot correctly be referred to as a database
3. A database is designed, built and populated with data for a specific purpose. It has an intended group of users and some pre conceived applications in which these users are interested.
4. A database can be of any size and of varying complexity
5. A database may be generated and maintained manually or it may be computerized
For small scale use, computerization is a waste but for large scale application computerization is very complex but highly effective in management, reporting monitoring etc
6. A computerized database may be created and maintained either by a group of application programs written specifically for that task or by a database management system
Commercial DBMS
ORACLE
SAP
DB
FOXPRO
MS ACCESS
Database Management System(DBMS)
A database management system(DBMS) is a collection of programs that enables users to create and maintain database. A DBMS helps in
Defining
Constructing
Manipulating
For various applications
Defining Database
Specifying the data types
Defining structures for the data
Specifying the constraints
Constructing Database
Building the database on a suitable medium
MS ACESS works on PC environment
SAP works on large systems
ORACLE can be customized to PC or LAN or even Distributed Systems
Manipulating Database
Querying the database to retrieve specific data
Updating the database to reflect changes in the mini world
Generating reports from the data
Database System
A database system consists of the DATABASE and the DBMS Software
MIS- Management Information System
DSS-Decision Support System
ERP-Enterprise wide Resource Planning solution
DCS-Distributed Control System
SCADA-Supervisory Control & Data Acquisition system
End to End Solution(Total Solution for all functional requirements)
Custom Solution(Partial solution for a particular purpose)
Characteristics of DBMS
Program-Data independence
The structure of the data files is stored in the DBMS catalog separately from the access programs
Program-Operation independence
Data Modeling
Data modeling is very essential to understand the extent and variety of information that are to be collected and stored to serve the intended purpose
The more deeper the understanding of the system functions, interdependence and the end user requirements or the purposes, the better will be the data models we develop
Data Modeling
Data modeling begins with the use of high level conceptual data models for database design
Data modeling involves four steps\
Requirement collection and analysis
Conceptual Design
Implementation of database
Physical design phase
Requirement collection and analysis
Interview with prospective database users
Understand and document their data requirements
Understand the functional requirements of the applications
Know the user defined operations(transactions) that will be applied to the database
Know the retrievals and updates needed
Conceptual Design
Create a conceptual schema for the database using a conceptual high level data model
-it will give a concise description of the data requirements of the users
-it do not contain the implementation details
-it can be used for communicating with the non technical users
-it can also be used to analyze the extent to which the users’ data requirements are met and that the conflicts are resolved/avoided
Implementation of database
3. The next step after data model/design is the actual implementation of the database, using a commercial DBMS
-for this we need data model mapping(logical design)
-this converts the high level data model to the implementation data model
-Fine-tuning the requirements considering the data availability, capability of the DBMS etc