Transcript Discovering Computers Fundamentals 2nd Edition

Chapter 9
Database
Management
Today
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Review 6 parts of the IT model
Understand what a database is
Demonstrate a database example using Access
Definitions:
o
Data – a collection of unprocessed items which can
include text, numbers, images, audio, and video.
o
Database – a collection of related data organized in a
manner that allows users to keep track of that data.
o
Database software (DBMS) – software that
allows users to create a digital database.
Think about it
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Name the data that would need to be kept track of
in…
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A telephone directory,
College course offerings,
Members of Congress,
Movie listing,
Party guest list?
Databases, Data and Information
What is a database?
Collection of data
organized so
you can access,
retrieve, and
use it
Database software
allows you to
Create
database
Add,
change,
and delete
data
p. 332
Database software
also called database
management system
(DBMS)
Sort
and
retrieve
data
Create
forms
and
reports
Next
The Hierarchy of Data
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Bit=smallest unit of data a
computer can understand
Character = 1 Byte or 8 bits
Field = a collection of related
characters
Records = a collection of related
fields
Data Files (Tables) = a collection
of related records
Database = a collection of related
files
bit
byte
field
record
file
DB
The Hierarchy of Data
What is a field?
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Combination of one or more
characters
Smallest unit of data user accesses
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p. 335 Fig. 9-3
Field size defines the maximum
number of characters a field can
contain
Field name uniquely identifies each
field
Data type specifies kind of data field
contains
Next
The Hierarchy of Data
What are common data (field) types?
Text
Numeric
(also called
alphanumeric)—letters,
numbers, or special
characters
AutoNumber
numbers
only
unique number automatically
assigned to each new record
Currency
dollar and cent amounts or
numbers containing decimal
values
Yes/No
only the values Yes or
No (or True or False)
p. 335
Date
Memo
month, day, year, and
sometimes time
lengthy text entries
Hyperlink
Web address that links to
document or Web page
Object
photograph, audio, video, or
document created in other
application such as word
processing or spreadsheet
Next
Consider the following DB examples:
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Personnel files
Customer purchases
Student records
Course offerings
Cookbook
Party guest list
What field names would you expect to find in each
DB?
The Hierarchy of Data
What is a record?
Group of
related fields
Key field, or primary key,
uniquely identifies each record
p. 336
Next
Name the unique identifiers…
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United states citizen
Mercer student
Person using computer
Cell phone
Email user
Web site
Web page
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Computer connected to •
the Internet
Social security number
Student ID
User name
Phone number
Email address
Domain name
URL
IP address
The Hierarchy of Data
What is a data file?
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Collection of related records stored on disk
records
p. 336
Member ID
First Name
Last Name
Address
City
State
2295
Donna
Vandenberg
1029 Wolf Avenue
Montgomery
AL
2928
Shannon
Murray
33099 Clark Street
Montgomery
AL
3376
Adrian
Valesquez
15 Duluth Street
Prattville
AL
3928
Jonah
Weinberg
P.O. Box 45
Clanton
AL
4872
Marcus
Green
22 Fifth Avenue
Auburn
AL
key
field
fields
Next
Maintaining Data
What is file maintenance?
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Procedures that keep data current
Adding records
Changing records
Deleting records
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p. 336
The DBMS makes file maintenance possible
Next
Database Management Systems
What are popular database management systems (DBMSs)?
p. 343
Next
Access specifics
There are 4 DB objects that are used by Access:
1. Tables – all of the data is stored in tables.
Tables are arranged in rows and columns.
2. Forms – provide an easy-to-use data entry
screen.
3. Reports – used to create professional reports
4. Queries – allow users to select a subset of
fields and records from one or more tables
rather than having to navigate many fields and
records from large DB’s.
Access example
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Example DB
Discuss
California was the first state to employ a controversial database. Based on
Megan’s Law — the statute named for a seven-year-old girl who was violated and
killed by paroled felon — the database listed the names and addresses of people
convicted of crimes against children. Today, many states employ similar
databases. In some communities, when a paroled offender moves in the police
inform the local school system, which in turn sends parents a notification that
includes a history, address, and picture of the wrongdoer. Touted as a valuable
tool in crime prevention, some feel that publishing this information makes it
impossible for an offender to lead a normal life and can result in vigilantism —
one paroled lawbreaker’s car was firebombed only days after his name was
released.
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Should a database of people paroled or released for crimes against
children be shared?
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Who should have access to the database?
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Should such a database include accused, but not convicted, offenders?
Discuss
For many students, the cost of college is even more depressing than
the quality of dining hall food. A free Web service can help students
find scholarships that match their qualifications, plans, and chosen
schools. When a student registers, the service queries a database of
more than 180,000 records in search of suitable scholarships and
then returns the results. Ironically, those least likely to benefit from
the scholarship search may be those who need it most. Because
students from poorer backgrounds usually have less computer
experience, they may be unaware of, or unable to access, the
scholarship search service.
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Who should assume the leading role in extending access to the
service?
How can the Web service be made more universally available?