1. Data Modeling and Database Design
Database Systems: Architecture and Components

2. What is the difference of Data and Information ?
Data - Distinct pieces of information,
information you store for future
reference
Data can exist in a variety of forms:
as numbers or text on pieces of paper,
as bits and bytes stored in electronic memory,
or as facts stored in a person's mind.
etc
What is the difference of Data and Information ?

3. Data vs. Information
Data: raw facts (employee names, hours worked etc). Represent real world things. They get value when some relationship is defined between them. Rules and relationships are set up to organize data into valuable information
Information: collection of facts organized in such a way that they have additional value beyond the facts themselves : information is value-added data
Turning data into information is a process – a set of logically related tasks to achieve a defined outcome
Knowledge is awareness and understanding of a set of information and the ways how it supports a specific task
The terms data & information are often used interchangeably. However, there is an important distinction: information is value-added data. Data is processed, organized or transformed to become information.
Data are raw facts. For example, if you write down your age & grade on an English test & hand it to me, I see 2 numbers – raw data. However, if you include the average age and average test score for your class, the data would have some meaning to me as a teacher… it would become information. Interestingly, your name and grade – data to me- could very well be information to you. In the context of your life or experiences, those 2 numbers alone would most likely have meaning.
Similarly, a grocery store manager would most likely find a list of every item sold today to be of little use – it is data. However, the amount that the store’s total sales are over or under planned sales would be information.

4. Data vs. Information

5. Valuable Information : result of data processing

6. Managing Data Difficulties in Managing Data
Amount of data increases exponentially.
Data are scattered and collected by many individuals using various methods and devices.
Data come from many sources – any problems here ?
Data security, quality and integrity are critical – why ?

7. Difficulties in Managing Data (continued)
An ever-increasing amount of data needs to be considered in making organizational decisions.
The Data Deluge

8. Terminology Data Information Metadata
Chapter 1 – Database Systems: Architecture and Components

9. Data Management Creation of data Retrieval of data
Update or modification of data
Deletion of data
For that, data must be accessed and, for the ease of access, data must be organized.
Chapter 1 – Database Systems: Architecture and Components

10. What Is a Database?
Databases in general are sets of data (information) that are arranged for easy access. Doesn’t have to be on a computer (is Rolodex a database ?).
Databases are good for tracking and reporting on most things in business – i.e. invoices, inventory, customers.
Examples: use a database to store and retrieve telephone numbers for customers, customer info, history of orders etc

11. Database: An Organized collection of Data
Filing cabinet
Electronic spreadsheet
Database in a computer
Storing Information
Every organization has some information needs. A library keeps a list of members, books, due dates, and fines. A company needs to save information about employees, departments, and salaries. These pieces of information are called data.
Organizations can store data on various media and in different formats—for example, a hard-copy document in a filing cabinet or data stored in electronic spreadsheets or in databases.
A database is an organized collection of information.
To manage databases, you need database management systems (DBMS). A DBMS is a program that stores, retrieves, and modifies data in the database on request. There are four main types of databases: hierarchical, network, relational, and more recently object relational.
Note: Oracle7 is a relational database management system and Oracle8 is an object relational database management system.

12. History of Data Management
1950
1960
1970
1980
1990
2000
File systems
Hierarchical DBMS
Network DBMS
Relational DBMS
Object-oriented DBMS
Chapter 1 – Database Systems: Architecture and Components

13. The Hierarchy of Data : data is usually organized in a hierarchy

14. Limitations of File-Processing Systems
Lack of Data Integrity Data integrity (data values are correct, consistent, complete, and current) is often violated in isolated environments.
Lack of Standards Organizations find it hard to enforce standards for naming data items as well as for accessing, updating, and protecting data.
Lack of Flexibility/Maintainability File-processing systems are not amenable to structural changes in data and are therefore dependent upon a programmer who can either write or modify program code.
Data are separated and isolated in a file processing environment
Data integrity (data values are correct, consistent, complete and current) is often violated in isolated environments
The structure of each file is embedded in the application programs
File processing systems lack flexibility and are not amenable to structural changes in data
Organizations find it hard to enforce standards for naming data in a file processing environment
File processing are dependent upon a programmer who can either write or modify program code
Chapter 1 – Database Systems: Architecture and Components

15. Limitations of File-Processing Systems (continued)
The limitations to file-processing systems are due to:
Lack of Data Integration Data are separated and isolated in a file-processing environment.
Lack of Program-Data Independence The structure of each file is embedded in the application programs.
Chapter 1 – Database Systems: Architecture and Components

16. The Traditional Database Approach : flat files to keep data of specific kind

17. So, What Is Desirable? Integrated data Data Independence
Not data in isolation to be integrated by the application program/programmer
Data Independence
Application program(s) immune to changes in storage structure and access strategy
Independent user views of data
Chapter 1 – Database Systems: Architecture and Components

18. Relational Database vs Flat Database Files
Flat file Database: puts all information in “one large table”. OK for small database. Consequences :
Leads to redundant data.
Potential of data corruption is high.
Relational Database: divides data into two or more tables and then relates the tables. For large databases, it is a faster, easier & more flexible use of your data.

19. Database approach involves a combination of hard ware and software
Database Approach : a pool of the same data shared by multiple applications
Database approach involves a combination of hard ware and software

20. The Database Approach
Database management system (DBMS) provides all users with access to all the data.
DBMSs minimize the following problems:
Data redundancy : The same data are stored in many places.
Data isolation : Applications cannot access data associated with other applications.
Data inconsistency : Various copies of the data do not agree.
Data redundancy: The same data are stored in many places.
Data isolation: Applications cannot access data associated with other applications.
Data inconsistency: Various copies of the data do not agree.

21. Database Approach (continued)
DBMSs maximize the following issues:
Data security : Keeping the organization’s data safe from theft, modification, and/or destruction.
Data integrity : Data must meet constraints (e.g., student grade point averages cannot be negative).
Data independence : Applications and data are independent of one another. applications and data are not linked to each other, meaning that different applications are able to access the same data.
Data security: Keeping the organization’s data safe from theft, modification,
and/or destruction.
Data integrity: Data must meet constraints (e.g., student grade point averages
cannot be negative).
Data independence: Applications and data are independent of one another.
applications and data are not linked to each other, meaning that
applications are able to access the same data.

22. Database Management Systems

23. Advantages of the Database Approach

24. More on Advantages of the Database Approach

25. Disadvantages of the Database Approach

26. Data Modeling and Database Models
Database design must reflect the enterprise’s business processes
When building the database , consider :
Content - What data should be collected?
Access - What data should be given to what users?
Logical structure - How will the data be organized to make sense to a particular user?
Physical organization - Where will the data actually be located?
Because a database design must reflect the enterprise’s business processes, several questions must be carefully considered when designing a database.
Clearly, the content of the database must be determined. However this may not be an easy question. Sometimes, it is very costly to collect and maintain particular data, so the importance and cost of the data must be considered as tradeoffs.
It is important to consider which users will be given access to which data, as well as the actions they will be allowed to perform on that data. For example, although an employee may be authorized to view is personnel record, he would not be authorized to change his salary.
The logical structure of the database is determined by identifying and grouping different data items and identifying relationships among the groups. This must be done in a way that makes sense to end users and makes it easy for them to get the data they need.
Finally, the actual data must be physically stored somewhere and in some physical storage organization. For example, decisions must be made about whether all data will be located in a single physical location or distributed among more than one computers or storage devices.

27. Data Models : relational data model is the basis for any relational database, but this model is not the only one
A data model defines how records are related, which affects how users can access the data.
Existing Data Models :
Hierarchical models
Network models
Relational models : the most popular and most widely used nowadays
A data model defines how records are related, which affects how users can access the data. Database management systems are classified by the type of data model they support. The three main data models are the hierarchical, network, and relational models. Relational models have become the most popular.

28. Hierarchical (Tree) Model is used for a Flat File database design

29. Hierarchical Databases
Early Database based on a hierarchical system much like your Windows filing system:

30. More on Database types : Network
Database Models:
2. Network :
A designer needs to set a predetermined structure : where to store what
Implement Owner/Member model
One has to be very familiar with database

31. Network Models

32. More on Database Types : Relational
Database Models:
3. Relational
Addresses limitations of other models
Each table represents an entity of its own, related to other entities ( other tables)
Independent of application which uses data

33. Entity-Relationship (ER) Diagram: graphical method to show organization and relationships between data

34. History of Data Management
In the 1970s, the Standards Planning and Requirements Committee (SPARC) of the American National Standards Institute (ANSI) proposed what came to be known as the ANSI/SPARC three-schema architecture: conceptual, internal and external schema.
Chapter 1 – Database Systems: Architecture and Components

35. Three Perspectives of Metadata in a Database
Chapter 1 – Database Systems: Architecture and Components

36. Conceptual Schema Core of the architecture
Represents the global view of the structure of the entire database for a community of users
Captures data specification (metadata)
Describes all data items and relationships between data together with integrity constraints
Separates data from the program (or views from the physical storage structure)
Technology independent
Chapter 1 – Database Systems: Architecture and Components

37. Internal Schema
Describes the physical structure of the stored data (e.g., how the data is actually laid out on storage devices)
Describes the mechanism used to implement access strategies (e.g., indexes, hashed addresses, etc.)
Technology dependent
Concerned with the efficiency of data storage and access mechanisms
Chapter 1 – Database Systems: Architecture and Components

38. External Schema
Represents different user views, each describing portions of the database
Technology independent
Views are generated exclusively by logical references
Chapter 1 – Database Systems: Architecture and Components

39. Physical and Logical Data Independence
Physical Data Independence
Definition: External views unaffected by changes to the internal structure
How?: Introduction of conceptual schema between the external views and the internal (physical) schema
Chapter 1 – Database Systems: Architecture and Components

40. Physical and Logical Data Independence (continued)
Definition: External views unaffected by design changes (growth or restructuring) in conceptual schema
How?: External views generated exclusively through logical reference to elements in the conceptual schema
Consequence: External views unaffected by changes to other external views
Chapter 1 – Database Systems: Architecture and Components

41. What is a Database System?
A self-describing collection of integrated records
Self-describing
The structure of the database (metadata) is recorded within the database system – not in the application programs.
Integrated
The responsibility for 'integrating' data items as needed is assumed by the DBMS instead of the programmer.
Chapter 1 – Database Systems: Architecture and Components

42. Characteristics of a Database System
A single, integrated set of files
Database Management System (DBMS)
A collection of general-purpose software that facilitates the process of defining, constructing, and manipulating a database for various applications
Chapter 1 – Database Systems: Architecture and Components

43. An Early View of a Database System
Chapter 1 – Database Systems: Architecture and Components

44. What is a Database Management System (DBMS)?
A DBMS is a collection of general-purpose software that facilitates the processes of defining, constructing, and manipulating a database.
The major components of a DBMS include one or more query languages; tools for generating reports; facilities for providing security, integrity, backup and recovery; a data manipulation language for accessing the database; and a data definition language used to define the structure of data.
Chapter 1 – Database Systems: Architecture and Components

45. Components of a Database System
Chapter 1 – Database Systems: Architecture and Components

46. Types of Database Systems
Number of users
Single-user
Desktop database system
Multi-user
Workgroup database system
Enterprise database system
Scope
Chapter 1 – Database Systems: Architecture and Components

47. Some Popular DBMS :
Excel **
Access
SQL Server
Oracle
MySQL

48. More on Popular RDBMS
MS Access ( small business, low cost, low security, small number of concurrent users)
MS SQL Server (middle to large companies, good security, good integration with Windows platforms, large number of concurrent users, relatively low cost)
Oracle (large businesses with high data storage and retrieval requirements, excellent security, scalability, performance, high cost)
DB2 (IBM) ( large businesses, usually deployed on mainframes and large scale workstations/clusters, requires professional management, high costs, very reliable)
Free public domain RDBMS ( mySQL, Cloudescape , more) : limited user interface tools, need high qualifications of personnel, from small to large businesses. Free ? No costs?

49. Popular Database Management Systems

50. System Development Life Cycle of a Database
Strategy
and
Analysis
Design a system basing on the model developed in the strategy and analysis phase.
Design
Build the prototype. Write and execute the command to create tables and objects. Develop user documentation and manual
Analyze business requirements. Build models of the system. Transfer business narrative into graphical representation of needs and rules. Confirm and refine the model with the analysts and experts
Build
and
Document
Transition
Production
System Development Life Cycle
From concept to production, you can develop a database by using the system development life cycle, which contains multiple stages of development. This top-down, systematic approach to database development transforms business information requirements into an operational database.
Strategy and Analysis
Study and analyze the business requirements. Interview users and managers to identify the information requirements. Incorporate the enterprise and application mission statements as well as any future system specifications.
Build models of the system. Transfer the business narrative into a graphical representation of business information needs and rules. Confirm and refine the model with the analysts and experts.
Design
Design the database based on the model developed in the strategy and analysis phase.
Build and Document
Build the prototype system. Write and execute the commands to create the tables and supporting objects for the database.
Develop user documentation, help text, and operations manuals to support the use and operation of the system.
Systematic approach to database development- transforms business requirements into an operational database

51. Quick Quiz
What is the difference between data, metadata and information?
What is the difference between sequential access and direct access? Give an example of each.
ANSWER: File.
What is data integrity and what is significance of a lack of data integrity? ANSWER: Data integrity.
: attribute
What is the difference between a database and a database management system?
ANSWER: Hierarchical.
What is the role of data models in database design? Which data model is the most flexible? ANSWER: Relational.
ANSWER: Entity-Relationship (ER) diagrams.

52. Quick Quiz
True or False: Oracle is the leading provider of database systems ANSWER: True
SWER: File.
What term is used to describe the degree of accuracy of data?
ASWER: Data integrity.
: attribute
Which data model uses a parent-child structure?
ANSWER: Hierarchical.
Which data model is the most flexible? ANSWER: Relational.
What is the most common data modeling technique?
ANSWER: Entity-Relationship (ER) diagrams.
ANSWER: SQL

53. Quick Quiz What is the term used to describe a collection of records?
ANSWER: File.
What term is used to describe the degree of accuracy of data?
ANSWER: Data integrity.
: attribute
Which data model uses a parent-child structure?
ANSWER: Hierarchical.
Which data model is the most flexible? ANSWER: Relational.
What is the most common data modeling technique?
ANSWER: Entity-Relationship (ER) diagrams.
True or False: Oracle is the leading provider of database systems ANSWER: True
ANSWER: SQL

54. Quick Quiz What is the term used to describe a collection of records?
ANSWER: File.
What term is used to describe the degree of accuracy of data?
ANSWER: Data integrity.
: attribute
Which data model uses a parent-child structure?
ANSWER: Hierarchical.
Which data model is the most flexible? ANSWER: Relational.
What is the most common data modeling technique?
ANSWER: Entity-Relationship (ER) diagrams.
True or False: Oracle is the leading provider of database systems ANSWER: True
ANSWER: SQL