Lecture1: Principles of Databases

1. Lecture1: Principles of Databases Ref. Chapter1 Prepared by L. NoufAlmujally

2. Chapter1 - Objectives • Meaning of the term database. • Meaning of the term Database Management System (DBMS). • Major components of the DBMS environment. • Users involved in the DBMS environment. • Advantages and disadvantages of DBMSs. Lecture1

3. Data • Data: Known facts that can be recorded and have an implicit meaning. ex)What does 3421 means? • facts about entities • Person's name, Phone, address, email, picture, … • Student's ID, name, subjects taken, results,… • Product's name, description, manufacturer, price,… • Book's publisher, author, title,… • facts about relationships • BADER lives in Riyadh • Nora bought a book from university books shop on 01/03/11 • Notice the different types of data • numbers, strings, text, date, time, timestamp, • Text, picture, audio, video, graphics … Lecture1

4. Data versus Information • Data itself has no meaning without meta data which describes data • For example : • 1012674, 28761, 153 • Does not give us any information, but knowing the meta data that explains data : Staff_ID, Phone Number, room number • Information: is the data you process in a manner that makes it meaningful. Lecture1

5. Database • Database A collection of logically related data, including metadata - ”data about data”, that describes data Data: name city birth Metadata: name - string, length<10 KhaledDammam 01/01/70 city – string, length<15 Sara Abha 01/03/01 birth – date, format DD/MM/YY Data is what you store in database Informationis what you retrieve from database • Two examples • all data required for the management of student records in a university. • all data required for the management of books and borrowers in a library. Lecture1

6. Types of Databases • Numeric and Textual Databases • Multimedia Databases • Geographic Information Systems (GIS) • Data Warehouses • Real-time and Active Databases Lecture1

7. Example of a Database(with a Conceptual Data Model) • Mini-world: Some part of the real world about which data is stored in a database. • Mini-world for the example: Part of a UNIVERSITY environment. • Some mini-world entities: • STUDENTs • COURSEs • SECTIONs (of COURSEs) • Grade Report • Prerequiests Lecture1

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10. Example of a Database(with a Conceptual Data Model) • 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 Lecture1

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12. Database Management Systems • Database Management System (DBMS) • A software system that enables users to create, maintain, and query the database • Most DBMSs now have facilities that make data access fast, reliable, secure and easy • Example DBMSs • Oracle • MS Access • MySQL Lecture1

13. Functions of a DBMS • Data Storage, Retrieval, and Update. • Storing data definition in the form of data dictionary • Transaction Support • Transaction: executing program or process that includes one or more database accesses, such as reading or updating of DB record • Concurrency Control Services. • Recovery Services. • Security protection against unauthorized access. • Maintain and develop the database system • Support for Data Communication. Lecture1

14. Application programs • Database Application : is a collection of data and the programs that allow the manipulation of these data to meet the information needs by an enterprise. • built on top of DBMS • to satisfy end users special requirements and preference Lecture1

15. Examples of Database Applications • Purchases from the supermarket • PNU Student Registration • PNU Library • Saudi Airline Reservation • Purchases using your credit card • Booking a holiday at the travel agents • Using the Internet Lecture1

16. Database System • Database System: The DBMS software together with the data itself. Sometimes, the applications are also included. (DB + DBMS + Application program) • To manage large amounts of data • Efficiently • Reliably • Securely • conveniently Lecture1

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19. Database Approach Lecture1

20. Main Characteristics of the Database Approach • Self-describing nature of a database system: A DBMS catalog stores the description of the database. The description is called meta-data). This allows the DBMS software to work with different databases. • Insulation between programs and data: Called program-data independence. Allows changing data storage structures and operations without having to change the DBMS access programs (application program). Lecture1

21. Main Characteristics of the Database Approach • Data Abstraction: A data modelis used to hide storage details and present the users with a conceptual view of the database. • Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. Lecture1

22. Main Characteristics of the Database Approach • Sharing of data and multiuser transaction processing : allowing a set of concurrent users to retrieve and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or completely aborted. • OLTP (Online Transaction Processing) is a major part of database applications. Lecture1

23. Components of DBMS Environment • Hardware • Can range from a PC to a network of computers. • Software • DBMS, operating system, network software (if necessary) and also the application programs. • Data • Procedures • Instructions and rules that should be applied to the design and use of the database and DBMS. • People Lecture1

24. Components of DBMS Environment

25. Database Users Communicate write Procedure DB Designer Design Application programmer Program Manage Application program DBMS Use DBA Naïve End user DB use Sophisticated End User

26. Database Users • Database administrators: responsible for: • authorizing access to the database • coordinating and monitoring the DB use • acquiring software, and hardware resources • monitoring efficiency of operations. Lecture1

27. Database Users • Database Designers: • responsible for defining the content, the structure, the constraints, and functions or transactions against the database. • They must communicate with the end-users and understand their needs. • Application Programmer • Implement programs meet the end user needs • Test , debug , document, and maintain transactions Lecture1

28. Database Users • End-users: they use the data for queries, reports and some of them actually update the database content. • Categories of End-users: • Naïve: (Queries / modifies data) • they make up a large section of the end-user population. • They use previously well-defined functions in the form of “canned transactions” against the database. • Examples: bank-tellers or reservation clerks. • Sophisticated : Forms requests in a database query language. Lecture1

29. Advantages of Using the Database Approach • Controlling redundancy in data storage and in development and maintenance efforts. • Sharing of data among multiple users. • Restricting unauthorized access to data. • Providing persistent storage for program Objects • Providing Storage Structures for efficient Query Processing Lecture1

30. Advantages of Using the Database Approach • Providing backup and recovery services. • Providing multiple interfaces to different classes of users. • Representing complex relationships among data. • Enforcing integrity constraints on the database. Lecture1

31. Disadvantages of Database Approach • Complexity • Cost of DBMS • Additional hardware costs • Performance • Higher impact of a failure Lecture1

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33. References • Fundamentals of Database Systems", RamezElmasri, Shamkant B. Navathe, Addison Wesley, The Latest Edition. Lecture1