C20.0001 Computer-Based Systems for Management Support

Kevin Brabazon

DDatabases : Fundamentals atabases : Fundamentals

Learning objectives for Session 11Learning objectives for Session 11

Relational database fundamentals

1. Get a basic idea about the difference between OLTP and OLAP

2. Understand what a database is, and how it is different from a DBMS and and a DBA

3. Understand what relational databases are

4. Identify and distinguish between the following parts of a relational database: tables, records, fields, field values

5. Understand three types of anomalies that arise from un-normalized data

6. Understand what primary keys and foreign keys are

7. Understand entities and primary keys

OLTP and OLAPOLTP and OLAP

OLTP: Online transaction processing

– Gathering input information

– Processing that information

– Updating existing information to reflect the gathering and processing that has taken place

OLAP: Online analytical processing

– Manipulating data to support decision making

Associated with a specific transaction: A repeated, routine event in the day-to-day working of an organization.

Example of a transaction: Placing an order at Amazon.com

Performed by transaction processing systems (TPS)

What are databases?

– Collections of information that are organized according to the logical structure of that information

DatabasesDatabases

Database management systems (DBMS)

– a software application with which you can create, store, organize and retrieve data from one or many databases

– Oracle 8, Access, Sybase, Informix, DB2

Database administrator (DBA)

– Person responsible for the development and management of an organization’s databases

Relational DatabasesRelational Databases

Last Name SS# DOB Major

Smith 100201122 06/11/84 IS

Kim 200202222 1/1/85 FIN

Davis 300201232 12/31/81 MKT

Pat 999132212 3/3/88 ACC

Student

Relational databases

– Databases that use a series of logically related two-dimensional tables to store their information

– Tables are comprised of fields/records, which in turn contain field values

TableField

Record

Field value

Relational Database

Tables

Records Fields

Field values

Bytes, bits

Last Name SS# DOB Major

Smith 100201122 06/11/84 IS

Kim 200202222 1/1/85 FIN

Davis 300201232 12/31/81 MKT

Pat 999132212 3/3/88 ACC

StudentTable

Field

Record

Field value

Relational DatabasesRelational Databases

Why do we need relational databases?Why do we need relational databases?

Problems arise when data is stored in one big file

Order# Date Customer ID Last Name First Name Address ISBN Book Name Author Price

1 9/1/03 C1001 Bezos Jeff 1 Amazon Plaza #0465039138 Code and other laws of cyberspace Lessig, Lawrence $25.00

2 9/2/03 C1004 Sproull LeeDean's Office, Stern School, New York #1573928895

Digital Copyright: Protecting Intellectual Property on the Internet Litman, Jessica $55.00

3 9/3/03 C1002 Student Pat Tisch LC-12, New York #0072952849 MIS in the Information Age Haag, Stephen $98.75

4 9/4/03 C1003 Gates BillMicrosoft Corporation, Redmond #0738206679

Linked: The New Science of Networks

Barabasi, Albert-Laszlo $34.95

5 9/5/03 C1003 Gates BillMicrosoft Corporation, Redmond #0738206083

Smart Mobs: The Next Social Revolution Rheingold, Howard $29.95

6 9/6/03 C1001 Bezos Jeff 1 Amazon Plaza #0738206083 Smart Mobs: The Next Social Revolution Rheingold, Howard $29.95

7 9/7/03 C1002 Student Pat Tisch LC-12, New York #1573928895Digital Copyright: Protecting Intellectual Property on the Internet Litman, Jessica $55.00

8 9/8/03 C1001 Bezos Jeff 1 Amazon Plaza #0738206083 Smart Mobs: The Next Social Revolution Rheingold, Howard $29.95

Anomalies in un-normalized dataAnomalies in un-normalized data

Insertion anomalies

– Inability to insert a piece of information about an object that can exist independently of another object without having to insert a piece of information about the other object

Deletion anomalies

– The loss of a piece of information about one object when a piece of information about a different object is deleted

Update anomalies

– A need to change the same piece of information about an object multiple times

–Example: Adding a new customer/book before it is ordered

–Example: Deleting an order => deleting a customer/book

–Example: Changing Bill Gates’ address

What’s wrong with this Data?What’s wrong with this Data?

StudentID#

StudentName

CampusAddress

Major Phone CourseID

CourseTitle

InstructorName

A121 Joy Egbert 100 N. State StreetMIS 555-7771 MIS 350 Intro. MIS Van Deventer

A121 Joy Egbert 100 N. State StreetMIS 555-7771 MIS 372 Database Hann

A121 Joy Egbert 100 N. State StreetMIS 555-7771 MIS 375 Elec. Comm. Chatterjee

A121 Joy Egbert 100 N. State StreetMIS 555-7771 MIS 448 Strategic MIS Chatterjee

A121 Joy Egbert 100 N. State StreetMIS 555-7771 MIS 474 Telecomm Gilson

A123 Larry Mueller 123 S. State StreetMIS 555-1235 MIS 350 Intro. MIS Van Deventer

A123 Larry Mueller 123 S. State StreetMIS 555-1235 MIS 372 Database Hann

A123 Larry Mueller 123 S. State StreetMIS 555-1235 MIS 375 Elec. Comm. Chatterjee

A123 Larry Mueller 123 S. State StreetMIS 555-1235 MIS 448 Strategic MIS Chatterjee

A124 Mike Guon 125 S. Elm MGT 555-2214 MIS 350 Intro. MIS Van Deventer

A124 Mike Guon 125 S. Elm MGT 555-2214 MIS 372 Database Hann

InstructorLocation

T240C

T240F

T240D

T240D

T240E

T240C

T240F

T240D

T240D

T240C

T240F

InstructorPhone

555-2222

555-2224

555-2228

555-2228

555-2226

555-2222

555-2224

555-2228

555-2228

555-2222

555-2224

Term

F'98

F'98

F'98

F'98

F'98

F'98

F'98

F'98

F'98

F'98

F'98

Grade

A

B

B

A

C

A

B

A

C

A

A

A124 Mike Guon 125 S. Elm MGT 555-2214 MIS 375 Elec. Comm. Chatterjee

A124 Mike Guon 125 S. Elm MGT 555-2214 MIS 474 Telecomm Gilson

A126 Jackie Judson224 S. Sixth StreetMKT 555-1245 MIS 350 Intro. MIS Van Deventer

A126 Jackie Judson224 S. Sixth StreetMKT 555-1245 MIS 372 Database Hann

A126 Jackie Judson224 S. Sixth StreetMKT 555-1245 MIS 375 Elec. Comm. Chatterjee

A126 Jackie Judson224 S. Sixth StreetMKT 555-1245 MIS 474 Telecomm Gilson

... ... ... ... ... ... ... ...

T240D

T240E

T240C

T240F

T240D

T240E

...

555-2228

555-2226

555-2222

555-2224

555-2228

555-2226

...

F'98

F'98

F'98

F'98

F'98

F'98

...

B

B

A

B

B

A

...

A normalized version of Amazon’s dataA normalized version of Amazon’s data

Normalization

– The process of assuring that a database can be implemented effectively as a set of two-dimensional tables

– Prevents insertion, deletion and update anomalies

Connecting tables togetherConnecting tables together

Primary keys

– A field (or group of fields in some cases) that uniquely describes each record in a table

– Examples: Customer ID, ISBN, Order#

Foreign keys

– A field that is a primary key in one table and appears in a different table (though not as the primary key)

– Examples: Customer ID in Orders

Integrity constraints

Rules that help ensure quality of information

Defining Entity Classes and Primary KeysDefining Entity Classes and Primary Keys

• Entity class - a concept - typically people, places, or things - about which you wish to store information and that you can identify with a unique key (called the primary key).

• Primary key - a field (or group of fields in some cases) that uniquely describes each record.

• Instance - an occurrence of an entity class that can be uniquely described.

Defining Entity Classes and Primary KeysDefining Entity Classes and Primary Keys

• What are the entity classes and primary keys for the report below?