Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Management Information SystemsBy Effy Oz & Andy Jones

www.cengage.co.uk/oz

Chapter 6: Databases and Data Warehouses

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Objectives

• Explain the difference between traditional file organisation and the database approach to managing digital data

• Explain how relational and object oriented database management systems are used to construct databases, populate them with data, and manipulate the data to produce information

• Enumerate the most important features and operations of a relational database, the most popular database model

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Objectives (continued)

• Understand how data modeling and design creates a conceptual blueprint of a database

• Discuss how databases are used on the Web• List the operations involved in transferring

data from transactional databases to data warehouses

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Managing Digital Data

• Businesses collect and dissect data• Data can be stored in powerful database format

– Easy access and manipulation• Databases have profound impact on business• Database technology integrated with Internet

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Traditional File Approach

• Traditional file approach: no mechanism for manipulating data

• Database approach: has mechanism for manipulating data

• Traditional approach inconvenient– High data redundancy– Low data integrity

• Data redundancy: duplication of data• Data integrity: accuracy of data

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Traditional File Approach (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach• Database approach: data organised as entities• Entity: object that has data

– People – Events– Products

• Character: smallest piece of data• Field: single piece of information about entity• Record: collection of fields

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach (continued)

• File: collection of related records• Database management system (DBMS):

program used to build databases– Populates with data– Manipulates data

• Query: message requesting access to data

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach (continued)

• Database has security issues• Database administrator (DBA): limits user

access to database– Requires users to enter codes

• DBMS bundled with fourth-generation languages

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Database Approach (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Database Models

• Database model: general logical structure– How records stored in database– Records linked differently in different models– Models constantly changing

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Relational Model

• Relational Model: consists of tables• Based on relational algebra

– Tuple: record– Attribute: field– Relation: table– Key: identifier field

• Used to retrieve records

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Relational Model (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Relational Model (continued)

• Primary key: unique key– Uniquely identifies record– Required in table

• Composite key: combination of fields– Serves as primary key

• Foreign key: shared field– Links tables

• Join table: composite of tables

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Relational Model (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Relational Model (continued)

• Table relationships with other tables• One-to-many relationship: one item in table

linked to many items in other table• Many-to-many relationship: many items in table

linked to many items of other table

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Object-Oriented Model

• Object-Oriented model: uses object-oriented approach

• Encapsulation: combined storage of data and relevant procedures– Allows object to be planted in different data

sets• Inheritance: creates new object by replicating

characteristics of existing (parent) object

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Object-Oriented Model (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Relational Operations• Relational operation: create temporary subset of

table• Create limited list or joined table list

– Select records based on conditions– Project columns– Join tables to create temporary table

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Structured Query Language

• Structured query language: language of choice for DBMSs

• Advantages– Standardised language– Used in many host languages– Portable

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Schema and Metadata

• Schema: plan– Describes structure of database– Names and sizes of fields– Identifies primary keys

• Data dictionary: repository of information about data

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Schema and Metadata (continued)

• Metadata: data about data– Source of data– Tables related to data– Field information– Usage of data– Population rules

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

The Schema and Metadata (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Data Modeling

• Databases must be carefully planned• Data modeling: analysis and organisation of

data– Proactive process– Develop conceptual blueprint

• Entity relationship diagram: graphical representation of relationships

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Data Modeling (continued)

• Entity relationship diagram– Boxes identify entities– Lines indicate relationship– Crossbars indicate mandatory fields– Circles indicate optional– Crows feet identify “many”

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Data Modeling (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Data Modeling (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Databases on the Web

• Web dependent on databases• Interface between Web and database required

– CGI– ASP– API

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Databases on the Web (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Data Warehousing

• Data collections used for transactions• Accumulation of transaction data useful• Data warehouse: large database

– Typically relational– Supports decision making– Data copied from transactional database

• Data mart: collection of data focusing on particular subject

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

From Database to Data Warehouse

• Transactional database not suitable for business analysis– Only current data– Not historic

• Data warehouse requires large storage capacity– Mainframe computers used– Scalability issue

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Phases in Building a Data Warehouse

• Begin building data warehouse after equipment secured– Extraction phase

• Create files from transactional database– Transformation phase

• Cleanse and modify data

• Loading phase• Transfer files to data warehouse

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Phases in Building a Data Warehouse (continued)

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Summary• organisations collect vast amounts of data• Database approach has advantages over

traditional approach• Character: smallest piece of data• File: collection of records• Designer must construct schema to construct

database

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Summary (continued)• Database management system enables database

construction and manipulation• Relational and object-oriented database models

have different advantages• Keys used to form links among entities• Object-oriented database maintains links

differently• SQL adopted as international standard

Use with Management Information Systems 1e

By Effy Oz & Andy Jones ISBN 9781844807581 © 2008 Cengage Learning

Summary (continued)

• Designers conduct data modeling to show required tables

• Databases often linked to Web• Data warehouses contain huge collections of historical

data• Data warehouse allows data extraction,

transformation, and loading• Invasion of privacy is exacerbated by database

technology