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.
