Transcript Data Representation

CHAPTER
Section A File And Database
Concepts
PARSONS/OJA
10
Databases
Computer Concepts 5th Edition
Parsons/Oja
Page 492
Databases
Chapter
10
 Data integrity
 Data is one of the company’s most
valuable assets
• British Airways
 Integrity: how accurate is the data?
• GIGO
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Databases
Chapter
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 Characteristics of valuable information
 Reliable
• Accurate
 Relevant
• To decision maker
 Timely
• Before decision is made
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Chapter
10
Section A File and Database
Concepts
Databases: What is a database?
 A database is a collection of information
 A field contains the smallest unit of
meaningful information, so you might call it
the basic building block for a structured
database
 Each field has a unique field name that
describes its contents
 A field can be either variable length or fixed
length.
Computer Concepts 5th Edition
Parsons/Oja
Page 494
Chapter
10
Section A File and Database
Concepts
Records: What is a record?
 A record refers
to a collection
of data fields
Computer Concepts 5th Edition
Parsons/Oja
Page 495
Chapter
Databases
10
 Updating data
 Adding records
• Each record must have a unique primary key
 Changing records
• Correct or update data
 Deleting records
• What if they are the building blocks for an object
you have created?
 Validating
• Checks data entry
 Social security number can’t be 45
Computer Concepts 5th Edition
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Page 493
Chapter
Databases
10
 Validating data (Field validation rules)
 Alpha/numeric
• Name can’t be 35 and phone number can’t be
CUBS-LOSE
 Range check
• Age can’t be 149
 Consistency
• Date terminated can’t be before date hired
 Completeness
• Can’t have 345-555 for a phone number
 Select from drop down list
• State
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Chapter
Databases
10
 File processing
 Each department maintains its own data
• Data redundancy
• Isolated data
 Database
 Users share the same data
• Reduces redundancy
 Integrity and extra storage
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Databases
Chapter
10
 Querys
 Allows users to retrieve desired data
 Query be example
•
•
•
•
CO
Or: meet either criteria
And: must meet both criteria
The NOT operator
 <>
 Forms
 Provides data entry screen to update database
 Reports
 Design a report for printing or to view
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Chapter
Databases
10
 Security
 Allows only authorized users
 Different levels of access privileges
 Identity theft
 Privacy
 Social security numbers
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Chapter
Databases
10
 Relational database
 Stores data in tables
• Table should only include one subject
 Employees
 Students
 Grades
 Housing
 Payroll
• Primary key: must be unique and not blank
 Stores relationships
• Must have common field
 Can’t create queries using fields from two
tables if no relationship
 Sorting
Computer Concepts 5th Edition
Parsons/Oja
Page 493
Chapter
Databases
10
 Database design
 Determine what data must be collected and
stored
 Don’t collect data that can be calculated
• Date of birth versus age
 Organize that data into fields
 Name versus
 Last Name and First Name
 Determine relationships between tables
Computer Concepts 5th Edition
Parsons/Oja
Page 493