Welcome

05G11389Management Information Systems

Session 2Data Bases

Who uses them??

Banks Airlines Business Libraries Governments, FBI, CIA, Interpol Artisists, film makers Scientists, DNA sequences…

Astronomers…Chemeists…

Who does not?

?????

8-12 billion USD annual IBM, Oracle, Informix, Sybase, NCR,

Microsoft, MySQL,…

History

1890 US Census asked Herman Hollerith to develop punch card machine.

Hollerith founded company, merged with another firm which became IBM.

Computer development fuelled by military in WW1, to track logistics and production of weapons. WWII, advanced optimization and cryptography

1960 US DOD commissions COBOL (Common business oriented language)

Codasyl (US Gov) and IMS (IBM and NASA)

History

"A Relational Model of Data for Large Shared Data Banks," Edgar F. (Ted) Codd Communications of the ACM 1970.

Data independence from hardware High level procedural language to

manipulate data IBM had IMS System R (SQL) Ingres (US Military, UC Berkeley)

History

Ingres & System R employees circulate through Silicon valley circles

1980 IBM SQL/DS hits market Codd awarded ACM Turing Award 1980s - Oracle marketing

demonstrates superiority of relational model

Terminology Data sources Database: persistent collection of data Database Management System (DBMS):

software that controls access to the database Database Administrator (DBA): person who

controls database Data Model: general structure of the data in

the database Data Language: commands used to define

the data model and give users access to the database; SQL (Structured Query Language)

Normal Forms

Non-normalized data 1NF

no repeating fields or groups of fields all values in field are “atomic”

2NF Already in 1NF Each non-key field is FD on entire primary key

3NF Already in 2NF no non-key element is FD on any non-key

element

Normal forms inclusive

ONF2

1NF

2NF

3NF

BCNF

4NF

5NF

Up 270+ Normal forms in Lit – Academic abstractions

To 1NF

users

name company company_address url1 url2

Joe ABC 1 Work Lane abc.com xyz.com

Jill XYZ 1 Job Street abc.com xyz.com

What if some companies have 3 URLS? 4, 5, …N?

1st Normal Form

users

userId name company company_address url

1 Joe ABC 1 Work Lane abc.com

1 Joe ABC 1 Work Lane xyz.com

2 Jill XYZ 1 Job Street abc.com

2 Jill XYZ 1 Job Street xyz.com

We have solved the URL problem,

But created another….

Eliminate horizontal redundancies

2nd Normal Form

users

userId name company company_address

1 Joe ABC 1 Work Lane

2 Jill XYZ 1 Job Street

urls

urlId relUserId url

1 1 abc.com

2 1 xyz.com

3 2 abc.com

4 2 xyz.com

Primary Key

Foreign Key

Eliminate vertical redundancies

3rd Normal Formusers

userId name relCompId

1 Joe 1

2 Jill 2

companies

compId company company_address

1 ABC 1 Work Lane

2 XYZ 1 Job Street

urls

urlId relUserId url

1 1 abc.com

2 1 xyz.com

3 2 abc.com

4 2 xyz.com

All columns must relate directly to the primary key

Finding Balance

email

PK address

FK1 user_idformat

phone

PK phone_id

FK1 type_idarea_codeNXXNCX

FK2 country_id

user

PK user_id

first_namelast_namenicknameunitstreet_numberstreet_namestreet_typequadrantweb_urlpicturenotes

FK1 postal_code

user_phone

PK,FK1 user_idPK,FK2 phone_id

extension

company

PK company_id

name

user_department

PK,FK1 user_idPK,FK2 department_id

type

PK type_id

type

country

PK country_id

Namephone_code

department

PK department_id

nameFK1 company_id

postal_code

PK postal_code

FK1 city_id

province

PK province_id

NameAbbreviation

FK1 country_id

city

PK city_id

nameFK1 province_id

Open Source…

www.opensource.org Linux (OS) Apache (Web Server) MySQL (DB) PhP (Scripting) JBoss (Web Server) Samba (file & content) OpenOffice (Office Apps.) Many more…

Open Source Pros..

Cost. As far as software acquisition costs go, open source products are free. Flexibility. Just like Linux, open source software frees companies from vendor lock-in. Close to the code. With open source, enterprise users can pinpoint problems in specific code and suggest patches to solve problems. Growing support. Vendors such as HP, Red Hat and Novell are enhancing support for open source products beyond Linux.

Open Source Cons.. Cost. While acquisition costs are free, corporate users

must pay for support and services, and there are often costs associated with training IT staff.

Integration. Today, users are on their own when it comes to integrating open source products into legacy infrastructure, although this is starting to change with companies as varied as Gluecode and HP rolling out support for open source stacks.

Capabilities. Today’s open source databases and application servers are technically very good, but still not up to par with heavy-duty commercial offerings such as DB2 or WebLogic.

Intellectual property. The SCO Group’s legal assault against Linux should serve as a warning shot for any company considering open source. Understand the open source license governing the product and what your rights and responsibilities are.