Oleary2012Comp ppt ch12

Chapter 12: Databases

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mputing Essentials 2012: Making IT Work for You

Competencies (Page 1 of 2)
• Distinguish between the physical and
logical views of data
• Describe how data is organized:
characters, fields, records, tables, and
databases
• Define key fields and compare batch
versus
real-time processing
• Describe databases, including the need
for databases, and database
management systems (DBMS)

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Competencies (Page 2 of 2)
• Describe the five common
database models:
hierarchical, network,
relational, multidimensional,
and object-oriented.
• Distinguish among individual,
company, distributed, and
commercial databases.
• Discuss strategic database
uses
and security concerns.

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Introduction to
Databases
• Like a library, secondary
storage
is designed to store

information
• End users need to understand
– How such stored information is
organized using data field,
records, files and databases
– The different types of databases
and structures

• Competent end users need to
be able to find information
that is stored in databases

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Data
• Examples of data include
– Facts or observations about people,
places, things, and events
– Audio, music, photographs, and
video

• Two ways to view data

– Physical view
– Logical view

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Data Organization
•
•
•
•
•
•
•
•

Character
Field
Record
File
Table
Database
Key Field

Batch Versus Real-Time Processing

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Key Field
• Unique identifier also known as
primary field
• Common examples
–
–
–
–
–

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Social Security Number
Student Identification Numbers
Employee Identification Numbers
Part Numbers
Inventory Numbers

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Batch Processing
• Batch processing
– Data is collected over a period of time
and the processing happens later all at
one time

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Real-Time Processing
• Real-time processing
– Also known as online processing because
it happens immediately during the
transaction

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Databases
• Collection of integrated data
– Logically related files and records

• Databases address data
redundancy
and data integrity
ã Need for databases
ã Database management

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Need for Databases
• Sharing
ã Security
ã Less data
redundancy
ã Data integrity

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Database Management
• DBMS engine
• Data definition
subsystem
– Data dictionary

• Data manipulation
subsystem
– Query-by-example
– Structured query language (SQL)

ã Application generation subsystem
ã Data administration subsystem

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mputing Essentials 2012: Making IT Work for You

DBMS Structure
• DBMS programs are designed to work
with data that is logically structured or
arranged
• Data models define rules and
standards for data in a database
• Five common data models are
–
–
–
–
–

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Hierarchical database
Network database
Relational database
Multidimensional database

Object-oriented database
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Hierarchical Database
• Fields or records are structured in
nodes
• Nodes are points connected like
branches
• One parent per node; a parent has
several
child nodes (one-to-many
relationship)

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Network Database
• Hierarchical node arrangement
• Each child node may have more than
one parent node (many-to-many
relationship)
• Additional nodes are called pointers
• Nodes can be reached through
multiple paths

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Relational Database
•
•
•

Data stored in table called a relation
Tables consist of rows and columns
Tables related via a common data
item

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Multidimensional
Database
• A variation and an extension of the
relational model to include additional
dimensions, sometimes called a data
cube
• Good for representing complex
relationships
• Advantages over relational
– Conceptualization
– Processing speed

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Object-Oriented
Database
• Works with unstructured data
–
–
–

Photographs
Audio
Video

• Objects contain both
data and instructions
• Organize using objects,
classes, entities,
attributes, and methods

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Types of Databases
• Individual
ã Company or shared
ã Distributed
ã Commercial

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Individual Databases
• Also called a microcomputer
database
• Integrated file collection for one
person usually under the
person’s direct control
• Generally stored on the user’s
hard-disk drive or on a LAN file
server

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