Post on 10-Jan-2016
description
Overview of the FLAT-FILE VS. DATABASE APPROACH
Overview of the FLAT-FILE VS. DATABASE APPROACH
FLAT-FILE PROBLEMSDATA STORAGE
DATA UPDATING
CURRENCY OF INFORMATION
TASK-DATA DEPENDENCYTHE DATABASE APPROACHNO DATA REDUNDANCY
SINGLE UPDATE
CURRENT VALUES
TASK-DATA INDEPENDENCE
CONTROLLING ACCESS TO THE DATABASETHE DATABASE MANAGEMENT SYSTEMA special software system that is programmed to know which data elements each user is authorized to access.
ELEMENTS OF THE DATABASE ENVIRONMENTUSERS
DATABASE ADMINISTRATOR
PHYSICAL DATABASE
USERSMETHODS OF USER ACCESSVia user programs prepared by systems professionals. The presence of the DBMS is transparent to the users.
Via direct query which requires no formal user programs. DATABASE MANAGEMENT SYSTEMTypical featuresProgram development
Backup and recovery
Database usage reporting
Database accessDATA DEFINITION LANGUAGEA programming language used to define the physical database to the DBMS. There are three levels called views:Internal view presents the physical arrangement of records in the database.Conceptual view (schema) represents the database logically and abstractly.User view (subschema) defines how a particular user sees the database.
DATA MANIPULATION LANGUAGEThe proprietary programming language that a particular DBMS uses to retrieve, process and store data. Inserting DML commands enables standard programs to be easily converted to work in a database environment.QUERY LANGUAGEThe query capability of the DBMS permits end users and professional programmers to access data in the database directly without the need for conventional programs.