1. Database Modeling Past and Present
Chapter1
Database Modeling Past and Present

2. Database Modeling Past and Present
The definition of a database
The definition of a database model
The evolution of database model
The hierarchical and network database models
The relational database model
The object and object-relational database models
Database model types
Database design objectives
Database design methods

3. Grasping the Concept of a Database
What is the difference between database and database model?
What is the difference between data and meta data?
The general view of a database
FirstName
LastName
Salary
Ahmed
Shaheen
5000
Data
Field
Type
Length
FirstName
Char 50
LastName
Salary
int 10
Metadata

4. Understanding a Database model
A database model is used to describe an organized and ordered set of information
The Relation between database model and the application
OLTP applications and OLTP models
Data warehouse application and data ware house models

5. The Evolution of Database Modeling
Database modeling techniques are:
File Systems
Hierarchical Database Model
Network Database Model
Relational Database Model
Object Database Model
Object-Relational Database Model

6. Flat file is a simple text file, containing no structure whatsoever
File Systems
No modeling techniques are applied
Data base is stored in flat files
Utilizing The structure of the operating system alone
Any searching through flat files has to be explicitly programmed
Any relationships and validation between flat files would have to be Programmed
The capabilities is poor an dlimitede
Flat file is a simple text file, containing no structure whatsoever

7. Hierarchical Database Model
The hierarchical database model is an inverted tree-like structure
The tables model support child-parent relationship
Each child table has a single parent
Each parent can have multiple child tables
Any entries in child tables can only exist where corresponding parent entries exist
Hierarchical database model support one-to-many relationships
Example of a hierarchical database model

8. Network Database Model
Network database model is a refinement of the hierarchical database model
Child tables are allowed to have more than one parent
Many –to-many relationships are allowed in addition to one-to-many relationships
One employee can be assigned many tasks and a task can be assigned to many employee
Mangers can be a part of both departments and companies

9. Relational Database Model
Any table can be accessed directly without having to access all parent objects
Any tables can be link together regardless of their hierarchical structure
Any table can be linked to both any number of parent tables and any number of child tables

10. Relational Database Management System (RDBMS)
Software Development Kit (SDK)
Complete management kit
End front tools
Example: Access
RDBMS is both the database engine and any other tools that come with it

11. The History of the Relational Database Model
The relational database model was invented by Dr. Codd.
The relational database began as a way of getting a group of data from a larger data set
This were done through a process called normalization
Normalization is a process which aim at removing duplication from the data
Normalization is composed of a number of steps called normal forms
The result was the Structured Query Language (SQL)
The development of the relational database model was done in terms of the movement of personal skills

12. Object Database Model
Object database model provides three dimensional structure to data
Object database model is efficient for finding unique items
Object database model performs poorly for finding more than single items
Object database model remove the need for types and many-to-many relationship replacement tables
If you can figure out who little pieces work individually, it makes the big picture

13. Object-Relational Database Model
The Object-relational database model was created in answer to conflicting capabilities of relational and object database models
Essentially, object database modeling capabilities are included in relational database
Summary of the evolution of database modeling
File System
No database model
Hierarchical
Allowing one-to-many relationships
Network
Allowing for special relationships
Relational
Allowing for individual element access anywhere in the database
Object
Handling high-speed application of small data items within large highly complex data sets
Object-relational
Including the most accountable aspects of object database into the structure of the relational database model

14. Examining the Types of Databases
Databases functionally fall into three categories:
Transactional
Decision support system (DSS)
Hybrid

15. Transactional Databases
The primary function of the database is to add new data, change existing data, deleting existing data
All operations are done in very small chunks, such individual records
Examples:
Client server database: low concurrency and low throughput
OLTP database: enormously high levels of concurrent database access

16. Decision Support System
DSS examples:
Data warehouse database: excessively large, OLTP is the source of the database
Data mart: a small subset of a larger data warehouse
Reporting database: a data warehouse but containing only active data ( more manageable and flexible)

17. A smaller hybrid database is often a more cost-effective
Hybrid Databases +
OLTP concurrency requirements
Data warehouse requirements
A smaller hybrid database is often a more cost-effective
This section presented:
What a database does
The function of the database can determine the way in which the database model is built

18. Understanding the Database Model Design
Design process involves putting your ideas on paper before actually constructing your object
Use every thing (flowcharts, pretty picture, ERD,…) to insure that what you intend to build is not only what you need but also will actually work
Poor design can cost a company more money than it is prepared to spend
Design is needed to ensure that it works before spending humungous amounts of money finding out that it does not

19. Defining the Objectives
A proper relational database model should:
Aim for a well-structured database model: simple, easy to read, easy to comprehend
Data integrity: data is not lost, destroyed when it should be
Support both planned and unplanned queries
Each table in a database model preferably represent a single subject or topic
Future growth must be a serious consideration
Future changes can be accommodated for
Minimize dependent between application and database model
You have to plan your steps and you also have to know what the steps are that you planning for

20. Looking at Methods of Database Design
Database modeling steps:
Requirements analysis: nature of the data, features required and output responses
Conceptual Design: draw pretty pictures, ERD diagrams, creation of tables
Logical design: Create database language commands
Physical design
Tuning phase: indexing, normalization, security features, ….
These separate steps are interchangeable, repeatable, iterative, and really anything able

21. Summary In this chapter, you learned about:
The difference between a database, a database model, and an application
The hierarchical and network database models
The relational database model
The object and object-relational database models
Why different database models evolved
The relational database model is the best all round option available
Database design depends on applications
Database types
Database design objectives and methods