Entity-Relationship Diagram Notes

Introducing the Database
 Data

versus Information constitute building blocks of information produced by processing data reveals meaning of data

 Data

 Information  Information  Good,  Good

timely, relevant information key to decision making decision making key to organizational survival

Database Management
 Database
 End

is shared, integrated computer structure housing: user data
 Metadata

 Database
 Manages
 Controls  Contains

Management System (DBMS)
Database structure access to data query language

Importance of DBMS
•
• •

Makes data management more efficient and effective
Query language allows quick answers to ad hoc queries Provides better access to more and bettermanaged data

•
•

Promotes integrated view of organization’s operations
Reduces the probability of inconsistent data

DBMS Manages Interaction

Database Design
 Importance
 Poor  Poor

of Good Design

design results in unwanted data redundancy

design generates errors leading to bad decisions

 Practical
 Focus

Approach

on principles and concepts of database design of logical design

 Importance

File Terminology
 Data
 Raw

Facts of characters with specific meaning

 Field
 Group

 Record
 Logically

connected fields that describe a person, place, or thing of related records

 File
 Collection

Simple File System

File System Critique
 File

System Data Management

 Requires

extensive programming in thirdgeneration language (3GL)

 Time

consuming ad hoc queries impossible to islands of information

 Makes  Leads

File System Critique (con’t.)
 Data

Dependence

 Change

in file’s data characteristics requires modification of data access programs

 Must

tell program what to do and how

 Makes

file systems cumbersome from programming and data management views

 Structural
 Change

Dependence

in file structure requires