1. Database Management Systems MIT 22033
Lesson 01 - Introduction
By S. Sabraz Nawaz

2. Introduction
A database management system (DBMS) is a software package designed to create and maintain databases
(examples?)
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

3. Introducing the Database
What is a database? A database is a collection of related data (University Database, Credit Card Processing Systems, Airline Reservation Systems, Banking System, etc.)
A database is a shared, integrated computer structure that stores a collection of: End-user data, that is, raw facts of interest to the end user.
Efficient data management typically requires the use of a computer database.
Metadata, or data about data, through which the end-user data are integrated and managed.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

4. Database Management System (DBMS)
A is a collection of programs that manages the database structure and controls access to the data stored in the database. In a sense, a database resembles a very well-organized electronic filing cabinet in which powerful software, known as a database management system, helps manage the cabinet’s contents.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

5. DBMS: Role and Advantages
The DBMS serves as the intermediary between the user and the database. The database structure itself is stored as a collection of files, and the only way to access the data in those files is through the DBMS.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

6. DBMS: Role
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

7. DBMS: Role…
The DBMS receives all application requests and translates them into the complex operations required to fulfill those requests. The DBMS hides much of the database’s internal complexity from the application programs and users.
The application program might be written by a programmer using a programming language such as Visual Basic.NET, Java, or C#, or it might be created through a DBMS utility program.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

8. DBMS: Advantages
Having a DBMS between the end user’s applications and the database offers some important advantages.
First, the DBMS enables the data in the database to be shared among multiple applications or users.
Second, the DBMS integrates the many different users’ views of the data into a single all-encompassing data repository.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

9. DBMS: Advantages - Improved data sharing
The DBMS helps create an environment in which end users have better access to more and better-managed data. Such access makes it possible for end users to respond quickly to changes in their environment
Concurrent accesses are scheduled by DBMS: users can think of the data as being accessed by one user at a time
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

10. DBMS: Advantages - Improved data security
The more users access the data, the greater the risks of data security breaches. Corporations invest considerable amounts of time, effort, and money to ensure that corporate data are used properly. A DBMS provides a framework for better enforcement of data privacy and security policies.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

11. DBMS: Advantages - Better data integration
Wider access to well-managed data promotes an integrated view of the organization’s operations and a clearer view of the big picture. It becomes much easier to see how actions in one segment of the company affect other segments.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

12. DBMS: Advantages - Minimized data inconsistency
Data inconsistency exists when different versions of the same data appear in different places.
The probability of data inconsistency is greatly reduced in a properly designed database.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

13. DBMS: Advantages - Improved data access
The DBMS makes it possible to produce quick answers to ad hoc queries.
From a database perspective, a query is a specific request issued to the DBMS for data manipulation—for example, to read or update the data.
Simply put, a query is a question, and an ad hoc query is a spur-of-the-moment question. The DBMS sends back an answer (called the query result set) to the application.
Example?
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

14. DBMS: Advantages - Improved decision making
Better-managed data and improved data access make it possible to generate better-quality information, on which better decisions are based. The quality of the information generated depends on the quality of the underlying data.
Data quality is a comprehensive approach to promoting the accuracy, validity, and timeliness of the data. While the DBMS does not guarantee data quality, it provides a framework to facilitate data quality initiatives.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

15. DBMS: Advantages - Increased end-user productivity
The availability of data, combined with the tools that transform data into usable information, empowers end users to make quick, informed decisions that can make the difference between success and failure in the global economy.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

16. DBMS: Advantages- Reduced Application Development Time
DBMS supports many functions common to applications that access the database
These applications are likely to be more robust than applications developed from scratch because many important tasks are handled by DBMS instead of being implemented by the application
Note: The advantages of using a DBMS are not limited to the few just listed. In fact, you will discover many more advantages as you learn more about the technical details of databases and their proper design.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

17. Types of Databases
A DBMS can support many different types of databases. Databases can be classified according to the number of users, the database location(s), and the expected type and extent of use.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

18. Types of Databases: Number of Users
A single-user database supports only one user at a time. In other words, if user A is using the database, users B and C must wait until user A is done. A single-user database that runs on a personal computer is called a desktop database.
A multiuser database supports multiple users at the same time. When the multiuser database supports a relatively small number of users (usually fewer than 50) or a specific department within an organization, it is called a workgroup database.
When the database is used by the entire organization and supports many users (more than 50, usually hundreds) across many departments, the database is known as an enterprise database.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

19. Types of Databases: Location
A database that supports data located at a single site is called a centralized database.
A database that supports data distributed across several different sites is called a distributed database.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

20. Types of Databases: Time and Usage
Based on how DBMS are used and on the time sensitivity of the information gathered from them:
Operational Database (Transactional or production database)
Data warehouse
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

21. Types of Databases: Time and Usage  Operational Database
Transactions such as product or service sales, payments, and supply purchases reflect critical day-to-day operations. Such transactions must be recorded accurately and immediately
A database that is designed primarily to support a company’s day-to-day operations is classified as an operational database (sometimes referred to as a transactional or production database).
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

22. Types of Databases: Time and Usage  data warehouse
A data warehouse focuses primarily on storing data used to generate information required to make tactical or strategic decisions. Such decisions typically require extensive “data massaging” (data manipulation) to extract information to formulate pricing decisions, sales forecasts, market positioning, and so on.
Most decision support data are based on data obtained from operational databases over time and stored in data warehouses. Additionally, the data warehouse can store data derived from many sources. To make it easier to retrieve such data, the data warehouse structure is quite different from that of an operational or transactional database.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

23. Example of a database: University DB
University database maintaining information concerning:
Students
Courses, and
Grades …
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

24. An example of a database that stores students and their grades of followed courses
Name
StudentNumber
Class
Major
Smith 17 1 CS
Brown 8 2
COURSE
CourseName
CourseNumber
CreditHouse
Department
Intro to Computer Science
CS 1310 4 CS
Data Structures
CS 3320
Discrete Mathematics
MATH 2410 3
MATH
Database
CS 3380
SECTION
Sectionaldentifier
CourseNumber
Semester
Year
Instructor 85
MATH 2410
Fall 98
King 92
CS 1310
Anderson
102
CS 3320
Spring 99
Knuth
112
Chang
119
135
CS 3380
Stone
GRADE_REPORT
StudentNumber
Sectionaldentifier
Grade 17
112 B
119 C 8 85 A 92
102
135
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

25. Example: University DB (contd…)
It shows the database structure and a few sample data.
It is organized as five files.
The STUDENT file – data on each student,
The COURSE file – data on each course,
The SECTION file – data on each section of a course,
The GRADE_REPORT file – data on grades that students receive in the various sections they have completed, and
The PREREQUISITE file – data on prerequisite of each course.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

26. Need for a DBMS
Traditional File System provided by the Operating System is insufficient to meet the requirements of enterprise applications
scenario:
A company has a large collection (500 GB) of data on database. This data is accessed concurrently by several employees. Questions about the data must be answered quickly, changes made to the data by different users must be applied consistently, and access to certain parts of the data must be restricted.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

27. When NOT to use a DBMS
High initial investment (DBMS is an expensive software package)
Applications use small amounts of data
Lack of resources (disk space, memory, etc.) to support a database
Single-user applications
Overhead for flexible querying, security, concurrent access & crash recovery is not required
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

28. Describing & Storing Data in a DBMS
A data model is a collection of high-level data description constructs used to model the application domain
Data model hides the low-level storage details
Most commercial database systems are based on the relational data model
It is easier to use a semantic data model to model an application domain. A well-known semantic data model is the Entity Relationship (ER) Model
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

29. Describing & Storing Data in a DBMS (cont.…)
In relational data model, the main construct is a relation.
A relation has fields that belong to it which contain the name & data type of each field
A description of data in terms of a data model is called the schema.
Every relation has a schema, which describes the name of the relation, name of each attribute (field or column), and the type of each column.
e.g. Students(sid: string, name: string, login: string,
age: integer, gpa: real)
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

30. An example instance of the Students relation
SID
Name
Login
Age
GPA
53666
SaNa 33
3.8
53668
Kumar 29
3.2
53670
Sanath 41
3.9
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

31. Describing & Storing Data in a DBMS (cont.….)
In addition to relational data model…
Hierarchical model
Network model
Object oriented model
Object relational model
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

32. Levels of Abstraction in a DBMS
To illustrate the meaning of data abstraction, consider the example of automotive design.
A car designer begins by drawing the concept of the car that is to be produced. Next, engineers design the details that help transfer the basic concept into a structure that can be produced. Finally, the engineering drawings are translated into production specifications to be used on the factory floor.
As you can see, the process of producing the car begins at a high level of abstraction and proceeds to an ever-increasing level of detail. The factory floor process cannot proceed unless the engineering details are properly specified, and the engineering details cannot exist without the basic conceptual framework created by the designer.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

33. Levels of Abstraction in a DBMS
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

34. Levels of Abstraction in a DBMS
DBMS is described at four levels of abstraction:
External Model
Conceptual Model
Internal Model
Physical Model
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

35. Levels of Abstraction in a DBMS: External Model
The external model is the end users’ view of the data environment. The term end users refers to people who use the application programs to manipulate the data and generate information. End users usually operate in an environment in which an application has a specific business unit focus.
Companies are generally divided into several business units, such as sales, finance, and marketing. Each business unit is subject to specific constraints and requirements, and each one uses a data subset of the overall data in the organization.
Therefore, end users working within those business units view their data subsets as separate from or external to other units within the organization.
A specific representation of an external view is known as an external schema.
Because data are being modeled, ER diagrams will be used to represent the external views.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

36. Levels of Abstraction in a DBMS: Conceptual Model
The conceptual model represents a global view of the entire database as viewed by the entire organization. That is, the conceptual model integrates all external views (entities, relationships, constraints, and processes) into a single global view of the data in the enterprise.
Also known as a conceptual schema, it is the basis for the identification and high-level description of the main data objects (avoiding any database model–specific details).
The most widely used conceptual model is the ER model.
Generally, the term logical design is used to refer to the task of creating a conceptual data model that could be implemented in any DBMS.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

37. Levels of Abstraction in a DBMS: Internal Model
Once a specific DBMS has been selected, the internal model maps the conceptual model to the DBMS.
The internal model is the representation of the database as “seen” by the DBMS. In other words, the internal model requires the designer to match the conceptual model’s characteristics and constraints to those of the selected implementation model.
An internal schema depicts a specific representation of an internal model, using the database constructs supported by the chosen database.
Because the internal model depends on specific database software, it is said to be software-dependent. Therefore, a change in the DBMS software requires that the internal model be changed to fit the characteristics and requirements of the implementation database model.
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

38. Levels of Abstraction in a DBMS: Physical Model
The physical model describes the way data are saved on storage media such as disks or tapes. The physical model requires the definition of both the physical storage devices and the (physical) access methods required to reach the data within those storage devices, making it both software- and hardware- dependent.
The storage structures used are dependent on the software (the DBMS and the operating system) and on the type of storage devices that the computer can handle.
Describes storage details
Summarizes how the relations described in the conceptual schema are actually stored on secondary storage devices such as disks and tapes
Decide what file organizations used to store the relations
Create indexes to speed up data retrieval operations
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

39. How does a DBMS do all this?
DBMS is a complex software package and the major components of a DBMS are shown
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

40. Queries In A DBMS With reference to a fictitious university database
What is the name of the student with student ID SEU/IS/98/MG/16?
What is the average salary of lecturers who teach the course with course ID MIT22033?
How many students are enrolled in course MIT22033?
Is there any student with a GPA less than 3.0 enrolled in course CS564?
These questions involving the data stored in a DBMS are called queries
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

41. Queries In A DBMS…
A DBMS provides a specialized language, called the query language in which queries can be posed
Relational calculus is a formal query language based on mathematical logic
Relational algebra is another formal query language, based on a collection of operators for manipulating relations, which is equivalent in power to the calculus
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

42. Database Design Process
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

43. Database Design Process
Database design process can be divided into 6 major steps: (given in Raghu’s text book)
Requirements Analysis
Conceptual Database Design
Logical Database Design
Schema Refinement
Physical Database Design
Security Design
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

44. Requirements Analysis
This step answers the following question:
“What users want from the database?”
what is going to be stored in the database
what applications are going to be built on top the database
what are the most frequently asked queries
Requirements Analysis
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

45. Requirements Analysis…
Result: A well-written concise document enumerating the user’s requirements
Requirements Analysis
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

46. Requirements Analysis…
For example: a library database…
Data to be stored can be…
Record of all books in the library
Record of members of the library
Students
Faculty
Other members
Record members’ borrowing information
Requirements Analysis
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

47. Requirements Analysis…
Some applications on top of the database can be…
Renewal service (may be on-line)
Borrowing-Lending service
Resource reservation system (may be on-line)
Resource request service (may be on-line)
Requirements Analysis
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

48. Conceptual Database Design
The information gathered in the requirements analysis phase is used to create a high-level description of the data in a conceptual data model. (Semantic Data Model, e.g. E-R Diagram )
Requirements Analysis
Conceptual Database Design
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

49. Logical Database Design
In this step, we determine the DBMS to implement the database & also the data model We utilize the conceptual schema created in the previous step and convert it into a schema of a particular data model (e.g. Relational Database Schema)
Requirements Analysis
Conceptual Database Design
Logical Database Design
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

50. Schema Refinement
The schema created by the logical database design phase is further refined for potential problems such as redundancies (e.g. Normalization)
Requirements Analysis
Conceptual Database Design
Logical Database Design
Schema Refinement
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

51. Physical Database Design
In this step, performance criteria are taken into consideration and further enhancements to the schema & creation of indexes are considered
Requirements Analysis
Conceptual Database Design
Logical Database Design
Schema Refinement
Physical Database Design
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

52. Security Design
In this step, different user groups and their roles are identified. Appropriate levels of access are then provided to the data ensuring that users have access to only the necessary data.
Requirements Analysis
Conceptual Database Design
Logical Database Design
Schema Refinement
Physical Database Design
Security Design
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

53. The story is… ER Diagram Conceptual Schema or Logical Schema
Requirements Analysis
Conceptual Database Design
Logical Database Design
Schema Refinement
Physical Database Design
Security Design
ER Diagram
Conceptual Schema or Logical Schema
Normalization
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

54. Assignment #01
What is a data model? Describe the data models with example
Clearly explain the architecture of a DBMS
Submission Deadline 31st December 2013
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL

55. Reference: Ramakrishnan, R. , & Gehrke, J. (2003)
Reference: Ramakrishnan, R., & Gehrke, J. (2003). Database management systems. Osborne/McGraw-Hill. (Pp. 03– 23)
MIT 22033, By: S.Sabraz Nawaz
B.Sc in MIT, SEUSL