1. 12
CHAPTER
DATABASES
Databases are the key to accessing information throughout our lives.
Used in hospitals, grocery stores, schools, department stores, IRS, and government agencies
Use them all the time (telephone directories, Christmas card lists), without realizing it… Just not familiar with technical term – database
DBMS Database Management System – actual software that organizes the database

2. Competencies (Page 1 of 2)
Distinguish between the physical and logical view of data
Describe how data is organized: characters, fields, records, files, and databases
Describe databases, database issues, and database management systems (DBMS)
Page 332

3. Competencies (Page 2 of 2)
Describe the five data models: hierarchical, network, relational, multidimensional, and object-oriented
Distinguish among individual, company, distributed, proprietary, and Web databases
Recognize strategic database uses and security concerns
Page 332

4. Data Facts or observations about people, places, things, and events
Two ways to view data
Physical view
Logical view
There are two ways to view data
Physical view – actual format and location; usually only very specialized computer professionals are concerned with the physical view
Logical view – focuses on the meaning and content of the data; end users and most computer professionals are concerned with this view
Page 334

5. Data Organization Character Field Record File Database
Understanding how data files work means understanding data organization, key fields, batch versus real-time processing, master versus transaction files and file organization.
Smallest to largest:
character – basic logical element; a single letter, number, or special character such as a punctuation mark
field – group of related characters; Last Name for example; a data field represents an attribute (description or characteristic) of an entity (person, place, thing, or object)
record – a collection of related fields
file – a collection of related records
database – is largest, collection of logically related records or objects
Key field – unique identifier to help locate data based on specific requests
Two main ways to process data: batch and real-time
Page 334

6. Key Field Unique identifier also known as primary field
Common examples
Social security number
Driver’s license
Credit card account
This field contains unique information, so that each record can be distinguished from any other
Used to integrate data and helps with finding records, sorting records, compiling information contained in the database
Page 336

7. Batch Versus Real-time Processing (Page 1 of 2)
Batch processing -- later
Batch Processing
Batch processing – data collected and stored over time (several hours, days, or even weeks) and then processed at once as a “batch”
Bank credit card
Even today mainframe time is dedicated to batch processing
Page 336

8. Batch Versus Real-Time Processing (Page 2 of 2)
Real-time processing -- now
Known as online processing
Occurs when data is processed at the same time the transaction occurs
Made possible by disk packs and direct access storage devices
Makes it possible to access the data quickly
Page 338

9. Need for Databases Sharing – one department to another
Security – passwords to access
Less data redundancy
Data integrity
Databases integrate data; DBMSs create, modify, and access databases using data dictionaries and query languages
Different departments within organization need access to same information; database gives flexibility for many people to access or for people to access only certain parts through use of password or “lock” on certain areas of database so that users can only read information
The advantages of having/using a database are:
Sharing – in organizations, information in one department can readily be shared with others
Security – Users are given passwords or access only to the kind of information they need
Less data redundancy – decrease of unnecessary duplication of data (or data redundancy) when several departments use the same database of information
Increased data integrity - Reduced likelihood of inconsistent, incomplete, or inaccurate data – data lacking integrity
Access data entry form
Page 339

10. Subsystems of a Database Management System
DBMS engine
Data definition subsystem
Data manipulation subsystem
Query-by-example
Structured query language (SQL)
Application generation subsystem
Data administration subsystem
Database management systems (DBMS) – enable users to create, modify, and gain access to data
Most common DBMS: Microsoft Access; Oracle common for Internet use and where more “power” is needed
DBMS engine – provides the bridge between the logical and physical view of the data; when users request data, the DBMS engine handles the details of actually locating the data
Data definition subsystem – Data dictionary terms used to describe the structure of the database: Field names; Field types; Field descriptions; Field “default” sizes
Data manipulation subsystem – provides tools for maintaining and analyzing data; query language: most common method to access database; ask a question of database to find data; two common forms
Query By Example (QBE)
Most common query language is SQL (structured query language)
Application generation subsystem – provides tools to create data entry forms and specialized programming languages that work with common and widely used programming languages
Data administration subsystem – helps manage the overall database; including maintaining security, providing disaster recovery support, and monitoring the overall performance of database operations
Larger organizations typically employ database administrators (DBAs), highly trained computer specialists to interact with the data administration subsystem; additional duties include determining processing rights or determining which people have access to what kinds of data in the database
Page 339

11. DBMS Structure
Data models define rules and standards for data in a database – the five data models are:
Hierarchical database
Network database
Relational database
Multidimensional database
Object-oriented database
Purpose of database is to integrate individual items of data into useful information; can be done sequentially, directly, or index-sequentially
Databases can be organized differently to best fit their use: hierarchical; network; relational; multidimensional; and object-oriented;
Each of the next five slides displays and explains the different data models
Page 340

12. Hierarchical Database
Fields or records are structured in nodes
Nodes are point connected like branches
One parent per node
Parent has several child nodes (one-to-many relationship)
Fields or records structured in nodes; viewed as branches of an upside-down tree
Each item is subordinate to its parent node; only one parent per node; parent can have several child nodes; sometimes described as a one-to-many relationship
The subordinate item is the child node to the parent
If parent node is deleted, all the child nodes are deleted
New parent node must be created before adding new child node
Limited by rigid structure; no connection between the child nodes
Airline reservation system
Return
Page 341

13. University Student System
Network Database
Hierarchical node arrangement
Each child node may have more than one parent node (Many-to-many relationship)
Additional nodes are called pointers
Also has hierarchical node arrangement -- but here child nodes may have more than one parent node, or a many-to-many relationship
The interconnected design allows for access via multiple pathways; i.e., more flexible
University Student System
Return
Page 341

14. Relational Database Most flexible
Data stored in table called a relation
Tables consist of rows and columns
Tables related via a common data item
Easy to use
No pre-determined access paths – Data stored in a collection of columns and rows called a table, or a relation
Tables may be electronically linked via a key field containing common data item
Most valuable feature of relational database: simplicity
Easy to add, delete, and modify the data
Easy to add to, delete, and modify table structures
Common for microcomputers:
Access, Paradox, dBASE, R: Base
Return
Page 342

15. Multidimensional Database
A variation and an extension of the relational model
Includes a hyper cube
Good for representing complex relationships
Advantages over relational
Conceptualization
Processing speed
Includes additional or multiple dimensions called a hyper cube
Data can be viewed as a cube having three or more sides and consisting of cells
Each side is considered a dimension of the data
Used for complex relationships between data
Complex relationships between data can be represented and efficiently analyzed
Conceptualization – provide users with an intuitive model in which complex data and relationships can be conceptualized
Processing speed – analyzing and querying a large multidimensional database is faster
Return
Page 343

16. Object-Oriented Database
Works with unstructured data
Photographs
Graphics
Audio
Video
Objects contain both data and instructions
Organize using objects, classes, entities, attributes, and methods
Objects – entities that contain both data and action that can be taken on that data
Classes – are similar objects grouped together
Entities – person, place, thing, or event that is to be described
Attributes – the description of entities; similar to fields
Methods – descriptions of how the data is to be manipulated
Could include photo of people in each record; could contain instructions for calculating monthly bills; could even tell when to print bill to send to customer/client
Return
Page 344

17. Types of Databases The five classifications of databases include:
Individual or microcomputer database
Company or shared
Operational
User
Distributed
Proprietary
Web database
Five kinds of databases whether large or small, limited or widely accessible:
Individual - often called a microcomputer database; integrated file collection for one person usually under the person’s direct control
Company or shared – may be stored on a mainframe and managed by a database administrator
Common operational databases contain information about company operations
Common user databases combine operational data with data from private (proprietary) sources
Distributed databases have data stored in multiple locations, but the data is accessible through communications networks
Proprietary databases (generally enormous to cover particular subjects) are created by an organization, and stored information is offered to others for a fee; examples include Dialog Information Services and Dow Jones Interactive Publishing; sometimes referred to as information utilities or data banks
Most of the proprietary databases are designed for organizational as well as individual use
Web database – a database available over the Web
Nearly every Web site you visit collects data about you and enters that data into a Web database
Page 345

18. Database Uses and Issues
Strategic uses
Special type of database called data warehouse
Data mining used to search database
Security
Databases are valuable
Protection necessary
Databases offer great opportunities for productivity; users must make constant effort to keep database reliable
Databases help users keep current and plan for the future, but keeping them secure is important.
Data collected from numerous sources
Stored in a data warehouse
By data mining, companies are looking for related information and patterns
Security may include armed guards to electronic verification of person through fingerprints or eye imaging
Databases may be supervised by a database administrator who is responsible for structure and performance and who has rights to access which data
Electronic fingerprint pads
Page 348

19. A Look to the Future Xperanto
Enhancement to searching for data
Access to structured (relational databases) and unstructured data (word processing and spreadsheet files)
IBM has announced technology that they hope will allow businesses to access many kinds of data from many locations from one database
Page 350

20. Discussion Questions (Page 1 of 2)
Describe the five logical data groups or categories.
What is the difference between batch processing and real-time processing?
Identify and define the five part of DBMS programs.
What are the five types of databases? Why does more than one kind of database exist?
Have students turn to the end of Chapter 12 in their textbooks to view the same “Open-Ended” questions/statements
Page 359

21. Discussion Questions (Page 2 of 2)
What are some of the benefits and limitations of databases? Why is security a concern?
Have students turn to the end of Chapter 12 in their textbooks to view the same “Open-Ended” questions/statements
Page 359