Entity-Relationship Diagram Notes

Satisfactory Essays
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

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