Transcript The Learning Objectives

THE DATABASE ENVIRONMENT

Definitions: Data, Information, Database,
Metadata
 File Processing Systems
 The Database Approach
 Components of the Database Environment
 Evolution of Database Systems
Data versus Information
Monthly Sales Report
for West Region
Sales Rep: Charles Mann
Emp No. 79154
Item
Qty Sold Price
TM Shoes 1200
$100
Some Definitions

Data: Meaningful facts, text, graphics, images,
sound, video segments.
 Database: An organized collection of logically
related data.
 Information: Data processed to be useful in
decision making.
 Metadata: Data that describes data.
Metadata for Class Roster
Descriptions of the properties or characteristics of the
data, including data types, field sizes, allowable
values, and documentation
Data Name
COURSE
SECTION
SEMESTER
NAME
ID
MAJOR
GPA
Data Type Length Value
Description
Alphanumeric
30
Course ID and name
Integer
1 {1,2,...,9} Section number
Alphanumeric
10
Semester and year
Alphanumeric
30
Student name
Integer
9
Student ID
Alphanumeric
4
Student major
Decimal
3 (0, 4.0) Student grade point average
Three file processing systems at
Pine Valley Furniture
Disadvantages of File Processing
Systems

Program-Data Dependence
– data descriptions are included with the application
programs that use the data

Data Redundancy (Duplication of data)
 Limited Data Sharing
 Lengthy Development Times
 Excessive Program Maintenance
SOLUTION: The DATABASE Approach
 Central
repository of shared data
 Data is managed by a controlling agent
 Stored in a standardized, convenient
form
Requires a Database Management System (DBMS)
Database Management System
Application
#1
Application
#2
Application
#3
DBMS
DBMS manages data
resources like an operating
system manages hardware
resources
Database
containing
centralized
shared data
The Database Approach
emphasizes the integration and sharing of data thru the
organization

An enterprise data
model is a graphical
model that shows the
high-level entities for
the organization and
the relationship among
those entities

– ORDER (O_ID, C_ID,
O_Date)
– ORDER_LINE (O_ID,
P_ID, QTY_Ordered)

– An entity is an object
or concept that is
important to the
business
– ERD
Relational Databases
A database application
is used to perform a
series of database
activities (create, read,
update, delete)
– The range of Database
Applications

Advantages
Segment from enterprise data model
Figure 3
Figure 3
Segment from enterprise data model
One customer may place many
orders, but each order is placed
by a single customer
 One-to-many relationship
Figure 3
Segment from enterprise data model
One order has many order
lines; each order line is
associated with a single order
 One-to-many relationship
Figure 3
Segment from enterprise data model
One product can be in many
order lines, each order line refers
to a single product
 One-to-many relationship
Figure 3 Segment from enterprise data model
Therefore, one order involves
many products and one product
is involved in many orders
 Many-to-many relationship
Order and Order_Line tables
Product and Customer tables
Figure 1-4 Order, Order_Line, Customer, and Product tables
Relationships established in special columns that provide links
between tables
Figure 1-5
Client/server
system for
Pine Valley
Furniture
Company
Advantages of the Database
Approach

Data Independence/Reduced Maintenance
– Data independence refers to the separation of data descriptions
from the application programs that use the data






Improved Data Sharing
Increased Application Development Productivity
Enforcement of Standards
Improved Data Quality (Constraints)
Better Data Accessibility/ Responsiveness
Security, Backup/Recovery, Concurrency
The Range of Database Applications

Personal Databases
– support one user
 Workgroup Databases
– a workgroup is a relatively small team of people who
collaborate on the same project or application
 Department Databases
– support the various functions and activities of a
department
 Enterprise Databases
– ERP work with the current operational data
– Data warehouses
 Internet Databases
Workgroup database
Figure 1-9 An
enterprise
data
warehouse
Components of the Database
Environment


CASE Tools
Repository - a centralized storehouse for all data definitions, data
relationships, and other system components

Database Management System (DBMS)
 Database - organized collection of logically related data
 Application Programs
 User Interface
 Data Administrators
 System Developers
 End Users
Components of
the Database Environment
Evolution of Database Technologies
Evolution of DB Systems


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



Flat files - 1960s - 1980s
Hierarchical – 1970s - 1990s
Network – 1970s - 1990s
Relational – 1980s - present
Object-oriented – 1990s - present
Object-relational – 1990s - present
Data warehousing – 1980s - present
Web-enabled – 1990s - present
Figure 1-2 Three file processing systems at Pine
Valley Furniture
Duplicate
Data
Problems with Data Redundancy
 Waste
of space to have duplicate data
 Causes more maintenance headaches
 The biggest Problem:
– When data changes in one file, could cause
inconsistencies
– Compromises data integrity
Problems with Data Dependency





Each application programmer must maintain their
own data
Each application program needs to include code
for the metadata of each file
Each application program must have its own
processing routines for reading, inserting, updating
and deleting data
Lack of coordination and central control
Non-standard file formats
Costs & Risks of the Database Approach

Up-front costs:
– Installation Management Cost and Complexity
– Conversion Costs

Ongoing Costs
– Requires New, Specialized Personnel
– Need for Explicit Backup and Recovery

Organizational Conflict
– Old habits die hard