Database

Your Interactive Guide
to the Digital World
Discovering
Computers 2012

Databases, Data, and Information
Database
• Collection of
data organized
in a manner
that allows
access,
retrieval, and
use of that
data
Data
• Collection of
unprocessed
items
• Text
• Numbers
• Images
• Audio
• Video
Information
• Processed data
• Documents
• Audio
• Images
• Video
Discovering Computers 2012: Chapter 10
2Page 514

3Pages 514 – 515
Figure 10-1

• Database software, often called a database
management system (DBMS), allows users to:
4Page 515
Create a computerized
database
Add, modify, and
delete data
Sort and retrieve data
Create forms and
reports from the data

• Valuable information should have the following
characteristics:
5Pages 516 - 517
Accurate Verifiable Timely Organized
Accessible Useful
Cost-
effective

The Hierarchy of Data
• Data is organized in layers
– Files, records, fields, characters
6Page 517
Figure 10-2

• A character is one byte
– Numbers, letters, space,
punctuation marks, or
other symbols
• A field is a combination
of one or more related
characters
– Field name
– Field size
– Data type
7Page 518
Figure 10-3

• Common data types include:
8Page 518
Text Numeric AutoNumber Currency
Date Memo Yes/No Hyperlink
Object Attachment

9Page 519
Figure 10-4
• A record is a group of related fields
– A primary key uniquely identifies each record
• A data file is a collection of related records

Maintaining Data
• Users modify a record to correct inaccurate data
or update old data
10Page 521
Figure 10-6

Maintaining Data
• When a record no longer is needed, a user deletes
it from a file
11Page 522
Figure 10-7

Maintaining Data
• Validation compares data with a set of rules or
values to find out if the data is correct
12Pages 522 - 524
Alphabetic/Numeric
check
Range check Consistency check
Completeness check Check digit Other checks

File Processing Versus Databases
13Pages 524 - 526
File processing system
• Each department has its
own set of files
• Used for many years
• Have data redundancy
• Isolate data
Database approach
• Programs and users share
data
• Reduce data redundancy
• Improve data integrity
• Share data
• Allows easier access
• Reduces development time
• Can be more vulnerable

Database Management Systems
• A DBMS provides several tools that allow users
and programs to retrieve and maintain data in the
database
14Page 528
Query language
Query by example
Form
Report generator

• A query language consists of simple, English-like
statements that allow users to specify the data to
display, print, or store
• Query by example (QBE) provides a GUI to assist
users with retrieving data
15Page 528

• A report generator allows users to design a report
on the screen, retrieve data into the report
design, and then display or print the report
16Page 531
Figure 10-16

A DBMS provides means to
ensure that only authorized users
access data at permitted times
•Access privileges
•Principle of least privilege
17Page 531

• A DMBS provides a variety of techniques to
restore the database to a usable form in case it is
damaged or destroyed
18Pages 531 - 532
Backup Log
Recovery
utility
Continuous
backup

Database Administration
Database analysts and administrators are responsible
for managing and coordinating all database activities
Database Analyst (DA)
Decides on proper field
placement, defines data
relationship, and identifies
users’ access privileges
Database Administrator (DBA)
Creates and maintains the data
dictionary, manages security,
monitors performance, and
checks backup and recovery
procedures
19Page 538

Database

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