Chapter 9 Database Management

Today

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

Name the data that would need to be kept track of in… A telephone directory, College course offerings, Members of Congress, Movie listing, Party guest list?

Add, change,

and delete data

Add, change,

and delete data

CreatedatabaseCreate

database

Sort and

retrieve data

Sort and

retrieve data

Createforms and

reports

Createforms and

reports

Databases, Data and InformationWhat is a database?

p. 332 Next

Database software allows you to

Database software allows you to

Collection of data organized so

you can access, retrieve, and

use it

Collection of data organized so

you can access, retrieve, and

use it

Database software also called database management system

(DBMS)

Database software also called database management system

(DBMS)

The Hierarchy of Data

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?

p. 335 Fig. 9-3 Next

Combination of one or more characters

Smallest unit of data user accesses 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

Yes/NoYes/Noonly the values Yes or No (or True or False)

HyperlinkHyperlinkWeb address that links to document or Web page

ObjectObjectphotograph, audio, video, or document created in other application such as word processing or spreadsheet

The Hierarchy of Data

What are common data (field) types?

p. 335 Next

CurrencyCurrencydollar and cent amounts or

numbers containing decimal values

DateDatemonth, day, year, and

sometimes time

MemoMemolengthy text entries

TextText(also called

alphanumeric)—letters, numbers, or special

characters

NumericNumericnumbers

only

AutoNumberAutoNumberunique number automatically assigned to each new record

Consider the following DB examples:

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?

p. 336 Next

Group of related fields

Key field, or primary key, uniquely identifies each record

Name the unique identifiers…

• United states citizen• Mercer student• Person using computer• Cell phone• Email user• Web site• Web page

• 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?

p. 336 Next

Collection of related records stored on disk

key field

records fields

22 Fifth Avenue

P.O. Box 45

15 Duluth Street

33099 Clark Street

1029 Wolf Avenue

Address

Auburn

Clanton

Prattville

Montgomery

Montgomery

City

ALWeinbergJonah3928

ALMarcus4872

ALValesquezAdrian3376

ALMurrayShannon2928

ALVandenbergDonna2295

StateLast NameFirst NameMember ID

Green

Maintaining Data

What is file maintenance?

p. 336 Next

Changing recordsAdding records

Deleting records

Procedures that keep data current

The DBMS makes file maintenance possible

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

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.  Should a database of people paroled or released for crimes against children be shared? Who should have access to the database? 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.

Who should assume the leading role in extending access to the service?

How can the Web service be made more universally available?