27-10-2012, 05:37 PM
DATABASE CONCEPTS
databaseconcepts.ppt (Size: 846 KB / Downloads: 32)
INTRODUCTION
What a Database Is and Is Not
Models of Reality
Why use Models?
A Map Is a Model of Reality
A Message to Map Makers
When to Use a DBMS?
Data Modeling
Process Modeling
Database Design
Abstraction
What a Database Is and Is Not
The word database is commonly used to refer to any of the following:
a collection of Word documents
a collection of Excel Spreadsheets
a very large flat file on which you run some statistical analysis functions
data collected, maintained, and used in airline reservation
data used to support the launch of a space shuttle
Models of Reality
A database is a model of structures of reality
The use of a database reflect processes of reality
A database system is a software system which supports the definition and use of a database
DDL: Data Definition Language
DML: Data Manipulation Language
A Message to Map Makers
A model is a means of communication
Users of a model must have a certain amount of knowledge in common
A model on emphasized selected aspects
A model is described in some language
A model can be erroneous
A message to map makers: “Highways are not painted red, rivers don’t have county lines running down the middle, and you can’t see contour lines on a mountain” [Kent 78]