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Week 2
September 7
• File-based Systems and Database
• Database Environment
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
What is Database?
2
• Definition:
"A shared collection of logically related data, and a
description of this data, designed to meet the information
needs of the organization."
• Data repository
Management system
controls access
Customer
transactions
Payroll
Vendors
Inventory
Operating
expenses
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Traditional File-Based System
3
• Definition:
"A collection of application programs that perform
services for the end-users such as the production of
reports. Each program defines and manages its own
data."
Customer
transactions
Operating
expenses
Inventory
Vendors
Payroll
Program
Program
Program
Program
Program
Report
Report
Report
Report
Report
One file, one application
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
4
For example…
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Invoice
No.
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R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Invoice
Anatomy of an Invoice
6
Invoice No.
Invoice
Stereos To Go
Date:
/
/
Account
No.
Customer
Customer:
Address:
City
Invoice
Date Shipped:
Item
Number
State
/
Zip Code
/
Product
Code
Product Description/Manufacturer
1
Items
purchased on
the Invoice
2
3
4
5
Products and Manufacturers
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Qty
Price
Invoice
Anatomy of an Invoice
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Invoice No.
Invoice
Stereos To Go
Date:
/
/
10001 051593 1005259412 William
Account
No.
Customer
Tell
2036 - 26 Street
Customer:
FD Invoice-File.
01 Invoice-Record.
05 Invoice-number
Date Shipped: 05
/ /Invoice-date
05 Cust-account-number
05 Cust-First-Name
05 Cust-Last-Name
05 Cust-Address
•
•
•
Products and Manufacturers
Address:
City
Invoice
Item
Number
Product
Code
1
Items
purchased on
the Invoice
2
3
4
5
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
State
Zip Code
Product Description/Manufacturer
PIC X(5).
PIC X(6).
PIC X(10).
PIC X(15).
PIC X(20).
PIC X(30).
Qty
Price
•••
Traditional File-Based System
Customer
Orders
Invoice Program
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Invoices
“A collection of application programs that perform services for the
end users such as the production of reports. Each program defines
and manages its own data.”
Customer
Accounts
File
Customer Account
Program
Account
Report
Customer
Mailing
List
Customer Mailings
Program
Mailing
List
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Data Redundancy
• Customer Order File
– Invoice number
– Customer account number
– Customer name, address, city, state, zip code
– Order date
– Product code, product description, price, unit
• Customer Account File
– Account Number
– Customer name, mailing address, city, state, zip code
• Customer Mailing List File
– Customer name, mailing address, city, state, zip code
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
9
File-Based Systems
• Records contain logically related data
• Limitations:
– Separation and isolation of data (one file, one program)
– Duplication of data
• Loss of data integrity - uncertainty of the correct
version of data and no consistency
– Data dependence - application program defines the data
– Incompatibility of file formats
– Fixed queries/proliferation of application programs little flexibility in meeting changing information needs
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
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Database
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• “A shared collection of logically related data (and a
description of this data), designed to meet the information
needs of an organization.”
Data and
Data
Definitions
Central Repository
Separation
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Applications
Data Abstraction
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• Separation between the data’s structure (definition) and the
application programs
COBOL
FD Master-File.
01 Master-Record.
05 ID
05 Customer-Fname
.
.
.
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Tightly binds the
data file and
program
PIC X(10).
PIC X(25).
Data Abstraction
• Separation between the data’s structure (definition) and the
application programs
COBOL
Tightly binds the
data file and
FD Master-File.
program
Data
01 Master-Record.
Output
05 ID
PIC
X(10).
Program
05 Customer-Fname PIC X(25).
.
.
.
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
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Data Abstraction
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• Separation between the data’s structure (definition) and the
application programs
Application programs can be run
on either the clients or server
Applications
Data and
Data
Definitions
DBMS
Central
Repository
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Organizing Data
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• Entity - distinct object (i.e., person, place, thing, concept or
event)
• Attribute - describes some aspect of the entity (object)
– Property of the entity
• Relationship - association between entities
Entity
Entity
Attributes
Customers
Account_number
Name
Address
Relationship
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Purchases
Invoice_number
Account_number
Purchase_date
Stereos to Go Database
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Management
Queries
Customer
Orders
Order Items
DBMS
Application
Programs
Products
Manufacturers
Central Repository
(Organizational resource)
• DDL
• DML
• Controlled access
Single Access Point
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
Other
Software
Multitude of
Applications
Components of a Database Environment
•
•
•
•
Hardware
Software: DBMS, application program and query software
Data: Organized in a schema, partitioned into subschemas
Procedures: Govern the design, access and use of the
database
• People: Administrators (DA, DBA), designers (logical and
physical), application developers and users (novice and
high-powered)
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
17
Advantages of the Database Approach
• Control of data redundancy
• Data consistency
• Greater informational gain, more information from the
same amount of data
• Sharing data, organizational resource (i.e., shared
resource)
• Improved data integrity, validity and consistency
• Improved access and security
• Enforcement of standards
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
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Advantages of the Database Approach
• Economy of scale, centralization and consolidation
• Balancing of conflicting requirements, DBA oversees data
and data definitions
• Improved data accessibility and responsiveness
• Increased productivity
• Improved maintenance through data independence
• Increased currency
• Improved backup and recovery services
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
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Disadvantages of the Database Approach
•
•
•
•
•
•
•
•
Complexity
Dedication of resources including
Size
technology and people infrastructures
Cost of DBMS
Additional hardware costs
Cost of conversion
Performance
Higher impact of failure
In a production environment, processing can be slow
R. Ching, Ph.D. • MIS Dept. • California State University, Sacramento
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