Information Systems Today: Managing in the Digital World TB3-1 3 Technology Briefing Database Management Modern organizations are said to be drowning in.

Information Systems Today: Managing in the Digital World TB3-1

3Technology Briefing

Database Management

“Modern organizations are said to be drowning in data but starving for information”

p. 509

COIS11011 WEEK 11

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Learning Objectives

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Learning Objectives

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Database Management for Strategic Advantage

• Database technology is vital to an organization’s success

• Variety of information collected and storedo Stock prices

o Potential customers

o Credit ratings of wholesalers

o Etc.

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Database Management for Strategic Advantage (II)

• Database technology used for:o Gathering and storing customer information

o Custom-tailoring catalogs and mailings

o Fueling electronic commerce

o Etc.

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Learning Objectives

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Database Foundations

• Then:o Card catalogs

o File cabinets

• Now:o DBMS

• Create• Store• Organize• Retrieve data

o E.g., Microsoft Access

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Database

• Databaseo Collection of related

data organized in a way to facilitate searches

o Entities

• Something you collect data about

• E.g.: people, books

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Record

• Contains data about a single entityo Similar to catalog

card

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Attributes

• Specific characteristic describing the entitieso E.g.: name and social

security number are attributes of a person

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Example: Entity Student• Entity represented as a table, with rows as records and

columns as attributes

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Advantages of the Database Approach

1. Program-data independence

2. Minimal data redundancy

3. Improved data consistency

4. Improved data sharing

5. Increased productivity of application development

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Advantages of the Database Approach (II)

6. Enforcement of standards

7. Improved data quality

8. Improved data accessibility

9. Reduced program maintenance

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Cost and Risks of the Database Approach

1. New, specialized personnel

2. Installation and management cost and complexity

3. Conversion costs

4. Need for explicit backup and recovery

5. Organizational conflict

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Effective Management of Databases• Database Administrator (DBA)

o Responsible for development and management of databases

•Works with system analysts and programmers

•Works with users and managers

• Implements security features

•Grants access rights

o One of the key actors in creating a successful database

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Entering Data

• Formso Enter data about a record

o Field in a form corresponds to attribute in a record

o Used to add, modify, or delete data

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Example: Computer-Based Form

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Querying Data• Query: used to retrieve information

• Structured Query Language (SQL) o Example: Display students who earned an “A”

o Writing SQL queries can become very complex

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Query by Example

• Simpler than SQL

• Drag-and- drop features

• Construct a sample of the data we would like to see

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Creating Database Reports• Report

o Compilation of data from the database

• Report generatorso Retrieve, manipulate, and display data

• Exampleo Quarterly sales for

a restaurant

• Adding

• Grouping

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Database Design

• Data need to be organized for retrieval and analysiso Key elements of a database

•Data

•Structure

• Data modelo A map or a diagram representing entities

and their relationships

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Example: Entities and Their Attributes

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Identifying Records

• Uniquely identifying records:o Primary Key

• Unique identifier • E.g.: Student ID number, social security number

o Combination primary key• Combination of two or more attributes • E.g.: identifying a student’s grade for a particular class for

a particular term

• Identifying records that share a common valueo Secondary Key

• Attribute not used as a primary key• E.g., Major

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Associations• Used to relate information between tables

• Needed to retrieve information

• Example: Basketball league database

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Example: Basketball League

• Each table contains important data

• No way to learn which team plays in a specific stadium

• Need to make associations

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Example: Basketball League

• Foreign keyso Attributes used

to link tableso Primary key in

one table, foreign key in another

o Need to create additional entity for many-to-many relationships

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Entity-Relationship Diagram• Used to show associations between entities

• Important when designing complex databaseso Entities: represented by boxes

o Relationships: represented by lines

Associations

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The Relational Model• Primary DBMS approach (RDBMS)• 3 dimensions

o Entities represented as 2-dimensional tables• Rows = records• Columns = attributes

o Tables joined based on common columns(3rd dimension)

• Good design eliminates redundancy

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Data Redundancy • Problematic if an attribute has to be changed

o Need to change in multiple locations

• E.g., instructor’s phone number

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Normalization• Eliminate unnecessary redundancy

o Create separate tables

o Data only needs to be changed in a single location

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Data Dictionary

• Document that specifies what data needs to be enteredo Attribute name

o Key or not

o Data type

o Valid values

• Can be used to enforce business rules

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Linking Website Applications to Organizational Databases

• Users can access a variety of data via a company’s web siteo Web services help in integration of

databases, regardless of physical location

• Need for adequate systems performance

• Get understanding of customer behavior