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Database Modeling Past and Present

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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

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