1. Database Management Systems Lecture # 01
Instructor:
Engr. Sana Ziafat

2. Introduction: What Is Database?
A very large, integrated collection of data.
Database: An organized collection of logically related data.

3. Types of Databases and Database Applications
Numeric and Textual Databases
Multimedia Databases
Geographic Information Systems (GIS)
Data Warehouses

4. Definitions
Data: Meaningful facts, text, graphics, images, sound, video segments
Information: Data processed to be useful in decision making
Metadata: Data that describes data

5. Figure: Data in Context

6. Figure: Summarized data
Useful information that managers can use for decision making and interpretation

7. Table: Metadata
Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and documentation

8. What is DBMS
A Database Management System (DBMS) is a software package designed to store and manage databases.
A DBMS is a data storage and retrieval system which permits data to be stored non-redundantly while making it appear to the user as if the data is well-integrated.

9. Database Management System
DBMS
Database
containing
centralized
shared data
Application #1 #2 #3
DBMS manages data resources like an operating system manages hardware resources

10. A simplified database system environment

11. Typical DBMS Functionality
Define a database : in terms of data types, structures and constraints
Construct or Load the Database on a secondary storage medium
Manipulating the database : querying, generating reports, insertions, deletions and modifications to its content
Concurrent Processing and Sharing by a set of users and programs – yet, keeping all data valid and consistent

12. Typical DBMS Functionality
Other features:
Protection or Security measures to prevent unauthorized access
“Active” processing to take internal actions on data
Presentation and Visualization of data

13. Example Mini-world for the example: Part of a UNIVERSITY environment.
Some mini-world entities:
- STUDENTs
- COURSEs
- SECTIONs (of COURSEs)
- (academic) DEPARTMENTs
- INSTRUCTORs
Some mini-world relationships:
- SECTIONs are of specific COURSEs
- STUDENTs take SECTIONs
- COURSEs have prerequisite COURSEs
- INSTRUCTORs teach SECTIONs
- COURSEs are offered by DEPARTMENTs
- STUDENTs major in DEPARTMENTs

15. Define UNIVERSITY database
Structure of the record
STUDENT ( Name , Number, Class, Major)
COURSE ( Name , Number, Credit, Dept.)
Data type of data element
Name: a string of characters
Number: integer
Grade: {A,B,C,D,F,I}
…..
Constraints
The sections that students take must be taught by some instructors.

16. Construct UNIVERSITY database Store data on storage medium
-store data for each student, course, section, grade repot, prerequisite
records in various files may be related to one another
Manipulate UNIVERSITY database
Query:
Retrieve the transcript ( a list of all courses and grades) of Smith.
Update:
Create a new section for the database course for this semester.

17. Disadvantages of File Processing
Program-Data Dependence
All programs maintain metadata for each file they use
Data Redundancy (Duplication of data)
Different systems/programs have separate copies of the same data
Limited Data Sharing
No centralized control of data
Lengthy Development Times
Programmers must design their own file formats
Excessive Program Maintenance
80% of of information systems budget

18. Figure: Three file processing systems at Pine Valley Furniture
Duplicate Data

19. Problems with Data Dependency
Each application programmer must maintain their own data
Each application program needs to include code for the metadata of each file
Each application program must have its own processing routines for reading, inserting, updating and deleting data
Lack of coordination and central control
Non-standard file formats

20. Problems with Data Redundancy
Waste of space to have duplicate data
Causes more maintenance headaches
The biggest Problem:
When data changes in one file, could cause inconsistencies
Compromises data integrity

21. SOLUTION: The DATABASE Approach
Central repository of shared data
Data is managed by a controlling agent
Stored in a standardized, convenient form
Requires a Database Management System (DBMS)

22. Advantages of Database Approach
Program-Data Independence
Metadata stored in DBMS, so applications don’t need to worry about data formats
Data queries/updates managed by DBMS so programs don’t need to process data access routines
Results in: increased application development and maintenance productivity
Minimal Data Redundancy
Leads to increased data integrity/consistency

23. Advantages of Database Approach
Improved Data Sharing
Different users get different views of the data
Enforcement of Standards
All data access is done in the same way
Improved Data Quality
Constraints, data validation rules
Better Data Accessibility/ Responsiveness
Use of standard data query language (SQL)
Security, Backup/Recovery, Concurrency
Disaster recovery is easier

24. Costs and Risks of the Database Approach
Up-front costs:
Installation Management Cost and Complexity
Conversion Costs
Ongoing Costs
Requires New, Specialized Personnel
Need for Explicit Backup and Recovery
Organizational Conflict
Old habits die hard

25. Conversion to database approach
Step 1:
Enterprise Data model: Graphical model that shows high level entities for organization and associations among these entities.
Step 2:
Relational Data Model: Defining tables for each entity.
Step 3:
Implement

26. Continued..
A data model is a collection of concepts for describing data.
A schema is a description of a particular collection of data, using the a given data model.
The relational model of data is the most widely used model today.
- Main concept: relation, basically a table with rows and columns.
- Every relation has a schema, which describes the columns, or fields

27. Segment from enterprise data model

28. One customer may place many orders, but each order is placed by a single customer
 One-to-many relationship

29. Therefore, one order involves many products and one product is involved in many orders
 Many-to-many relationship

30. Database Users
Users may be divided into those who actually use and control the content (called “Actors on the Scene”) and those who enable the database to be developed and the DBMS software to be designed and implemented (called “Workers Behind the Scene”).

31. Database Users Actors on the scene
Database administrators: responsible for authorizing access to the database, for co-ordinating and monitoring its use, acquiring software, and hardware resources, controlling its use and monitoring efficiency of operations.
Database Designers: responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end-users and understand their needs.
End-users: they use the data for queries, reports and some of them actually update the database content.

32. Categories of End users
Sophisticated Users: these include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities. Many use tools in the form of software packages that work closely with the stored database.
Naive Users: They don’t need to know any details of structure. They access the database by writing simple commands or by choosing operations from menus.

33. Workers behind the scene
Persons whose job involves design, development, operation,and maintenance of the DBMS software and system environment.
DBMS designers and implementers: Design and implement the DBMS software package itself.
Tool developers: Design and implement tools that facilitate the use of the DBMS software. Tools include design tools, performance tools, special interfaces,etc.
Operators and maintenance personnel: Work on running and maintaining the hardware and software environment for the database system.

34. Figure Client/server system

35. The Range of Database Applications
Personal Database – standalone desktop database
Workgroup Database – local area network (<25 users)
Department Database – local area network ( users)
Enterprise Database – wide-area network (hundreds or thousands of users)

36. Figure: Typical data from a personal computer database

37. Figure: Workgroup database with local area network

38. Figure : An enterprise data warehouse

39. Figure: Components of the database environment

40. Evolution of DB Systems
Flat files s s
Hierarchical – 1970s s
Network – 1970s s
Relational – 1980s - present
Object-oriented – 1990s - present
Object-relational – 1990s - present
Data warehousing – 1980s - present
Web-enabled – 1990s - present

41. When not to use DBMS Main costs of using a DBMS:
- High initial investment in hardware, software,training
and possible need for additional hardware.
- Overhead for providing generality, security, recovery, integrity, and concurrency control.
- Generality that a DBMS provides for defining and processing data.
When a DBMS may be unnecessary:
- If the database and applications are simple, well defined, and not expected to change.
- If there are stringent real-time requirements that may not be met because of DBMS overhead.
- If access to data by multiple users is not required.

42. Quick Review CASE Tools – computer-aided software engineering
Repository – centralized storehouse of metadata
Database Management System (DBMS) – software for managing the database
Database – storehouse of the data
Application Programs – software using the data
User Interface – text and graphical displays to users
Data Administrators – personnel responsible for maintaining the database
System Developers – personnel responsible for designing databases and software
End Users – people who use the applications and databases

43. ?????
Indicate whether there is one-to-many or many-to-many relationships?
STUDENT and COURSE( student registers for course)
BOOK and BOOK COPY (books have copies)
INSTRUCTOR and COURSE