Databases, Data and Information

(1)

(2)

Add, change, and delete

data

Add, change, and delete

data retrieve

data

Sort and retrieve

data

Databases, Data and Information

What is a

database

?

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

(3)

Data and Information

How are

data

and

information

related?

 _Data_{is raw facts}

 _Information_{is data that is organized and meaningful}

(4)

Data and Information

What is data integrity?

 _{Defines the quality of the}

data

 Garbage in, garbage out (GIGO)—computer phrase that means you cannot

create correct information

from incorrect data Garbage out

Garbage in

(5)

Useful

Accessible

Organized

Data and Information

What are the qualities of valuable information?

Timely

Verifiable

Accurate

Cost-effective

(6)

The Hierarchy of Data

What is a hierarchy?

 _{Database contains files, file contains records, record}

(7)

The Hierarchy of Data

What is a

field

?

 _{Combination of one or more characters}  _{Smallest unit of data user accesses}

 Field name_{uniquely identifies each field}

 Field size defines the maximum number of characters a field can contain

(8)

Yes/No

only the values Yes or No (or True or False)

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

The Hierarchy of Data

What are common data types?

Currency

dollar and cent amounts or numbers containing decimal values

Date

month, day, year, and sometimes time

Memo

lengthy text entries

Text

(also called alphanumeric)— letters, numbers, or special

characters

Numeric

numbers only

AutoNumber

(9)

The Hierarchy of Data

What is a

record

?

Group of related fields

(10)

The Hierarchy of Data

What is a

data file

?

 _{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 Last Name

First Name Member ID

(11)

Maintaining Data

What is

file maintenance

?

Changing records Adding records

Deleting records

(12)

Maintaining Data

Why do you add records?

(13)

Maintaining Data

Why do you change records?

 _{Correct inaccurate data}

(14)

Maintaining Data

Why do you delete records?

 _{When record no longer is needed}

 _{Some programs remove record immediately, others}

(15)

Maintaining Data

What is

validation

?

 _{Process of comparing data with a set of rules to find out}

if data is correct

 _{Reduce data entry errors and enhance data integrity}

(16)

Consistency Check

tests for logical

relationship between two or more fields

Consistency Check tests for logical

relationship between two or more fields

Maintaining Data

What are the types of

validity checks

?

Range Check

determines whether number is within specified range

Range Check

determines whether number is within specified range

Completeness Check

verifies that a required field contains data

Completeness Check

verifies that a required field contains data Check Digit

number(s) or

character(s) appended to or inserted into a primary key value to confirm accuracy of primary key value

Check Digit number(s) or

character(s) appended to or inserted into a primary key value to confirm accuracy of primary key value

Alphabetic/

Numeric Check

ensures correct type of data entered

Alphabetic/

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Isolated data— data stored in separate files so

it is difficult to access

Isolated data— data stored in separate files so

it is difficult to access

File Processing Versus Databases

What is a

file processing system

?

Data redundancy—

same fields stored in multiple files

Data redundancy—

same fields stored in multiple files

Each

department or area within organization has

own set of files Each

department or area within organization has

own set of files

May have weaknesses May have weaknesses Records in one

file may not relate to records in any other file

(18)

File Processing Versus Databases

What is the

database approach

?

 _{Many programs and users can share data in database}

(19)

File Processing Versus Databases

What are the strengths of the database approach?

Reduced data redundancy

Improved data integrity

Shared data

Easier access

Reduced development

time

Reduced development

(20)

File Processing Versus Databases

How do a database application and a file processing

(21)

Database Management Systems

(22)

Database Management Systems

What is a

data dictionary

?

 _{Contains data about each file in database and each field}

(23)

Database Management Systems

What is a

query

?

 _{Request for specific}

data from a database

 _{Query language}

consists of simple,

English-like statements that allow users to

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Database Management Systems

What is a

query by example (QBE)

?

 _{Program retrieves records that match criteria entered in}

form fields

 _{Has a graphical user interface that assists users with}

(25)

Database Management Systems

What is a

form

?

 _{Window on screen that provides areas for entering or changing}

data in database

 _{Used to retrieve and maintain data in a database}

(26)

Database Management Systems

What is a

report generator

?

 _{Allows user to design a report on screen, retrieve data}

into report design, then display or print reports

 _{Also called report}

(27)

Database Management Systems

What are

backup

and

log

?

 _Backup_{is a copy of the entire database}

 _Log_{is a listing of activities that change database contents}

(28)

Database Management Systems

What is data security?

user can view data, but cannot change

it

user can view data, but cannot change

it DBMS provides

means to ensure only authorized users can access data at permitted

times

DBMS provides means to ensure only authorized users can access data at permitted

times

Access privileges define activities that specific user or group of users

can perform

Access privileges define activities that specific user or group of users

can perform

user can view and change

data

user can view and change

(29)

Relational, Object-Oriented, and Multidimensional Databases

What is a

data model

?

 _{Rules and standards that define how database}

organizes data

 _{Defines how users view organization of data}  _{Three popular data models}

 Relational

 Object-oriented

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What is a

relational database

?

 _{Stores data in tables that consist of}_rows_and_columns

 Each row has primary key

 Each column has unique name  _{Stores data relationships}

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What is a

relationship

?

 _Connection

(32)

What is

Structured Query Language (SQL)

?

 _{Allows you to manage, update, and retrieve data}

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What is an

object-oriented database (OODB)

?

Advantages

Often uses object query language (OQL) Stores data in objects

Object is item that contains data, as well as actions that read or process data

Can store more types of data

Can access data faster

(34)

What is a

multidimensional database

?

Stores data in dimensions

Allow users to analyze any view of data

(35)

What is a

data warehouse

?

Data mart is smaller version of

data warehouse

Uses multidimensional

databases

Huge database system that stores and manages data

required to analyze historical and current transactions

Quick and efficient

way to access large

amounts of data

(36)

Web Databases

What is a Web database?

 _{Database you access through the Web by filling in a form on a}

Web page

 _{Usually resides on a database server, a computer that stores}

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3. Design the records and fields

for each table

2. Design the tables

1. Determine the purpose of the database

4. Determine the

relationships among the tables

4. Determine the

relationships among the tables

 Design tables on paper first  Each table should contain

data about one subject

Database Administration

What are guidelines for developing a database?

 Be sure every record has a unique primary key

 Use separate fields for logically distinct items

 Do not create fields for information that can be derived from entries in other fields

 Allow enough space for each field  Set default values for frequently

(38)

Database Administration

What is the role of the database analyst and

administrator?

Database analyst (DA)

Database analyst (DA) Database administrator (DBA)

Database administrator (DBA)

 Decides proper placement

of fields, defines relationships, and

identifies users’ access privileges

 Creates and maintains data

dictionary, manages database security, monitors database

performance, and checks backup and recovery