1. Course Introduction Ria Mae G. Corda ITB322 (Lecture) 2 nd Semeseter, AY 2009 - 2010

2. Outline Introducing the database and related terms A REAL LIFE example The database approach The database actors

3. Outline Behind the scene The DBMS advantage When NOT to use DBMS Summary

4. Introducing the database and related terms Traditional Database Applications – Information is stored textually or numerically Multimedia Database Applications – Images, audio clips and video streams can be stored – Geographic information systems – Data warehouses – Online analytical processing (OLAP) – Real-time/Active database technology

5. Introducing the database and related terms Database – Collection of related data Data – Known facts – Can be recorded – Have implicit meaning

6. Introducing the database and related terms Properties of a database – Represents some aspect of the real world – Logically coherent collection of data with inherent meaning – Designed, built and populated for a specific purpose

7. Introducing the database and related terms A database may be maintained manually or it may be computerized – In this course we are only concerned about computerized databases – A computerized database may be created an manipulated using application programs or by a database management system

8. Introducing the database and related terms Database Management System (DBMS) – A collection of programs that enables users to create and maintain a database – A general-purpose software system that facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications

9. Introducing the database and related terms Defining a database – Involves specifying the data type, structures, and constraints of the data to be stored in the database. – The database definition is also stored in the database Meta-data is the database catalog or dictionary

10. Introducing the database and related terms Constructing the database – The process of storing the data on some storage medium controlled by the DBMS

11. Introducing the database and related terms Manipulating a database – Includes querying the database for information retrieval, updating the database to reflect changes in the real world, and generating reports from the data.

12. Introducing the database and related terms Sharing a database – Allows multiple users and programs to access the database simultaneously.

13. Introducing the database and related terms Application program – Accesses the database by sending queries or requests for data to the DBMS

14. Introducing the database and related terms Query – Typically causes for some data to be retrieved. Transaction – Causes some data to be read and some data to be written into the database.

15. Introducing the database and related terms Protection – System protection against hardware or software malfunction, – Security protection against unauthorized or malicious access. Maintenance – Allowing the system to evolve as requirements change over time

16. Introducing the database and related terms It is not necessary to use general-purpose DBMS software to implement a computerized database. Database system – The database and the DBMS software together

17. A REAL LIFE example The SCENARIO – A UNIVERSITY database for maintaining information concerning students, courses, and grades in a university environment – Has five files: STUDENT, COURSE, SECTION, GRADE_REPORT, PREREQUISITE

18. A REAL LIFE example Defining the database – We must define the data types of each data element in each record

19. A REAL LIFE example Constructing the database – We store the data regarding each student, course, section, grade report, and prerequisite

20. A REAL LIFE example Manipulating the database – Involves querying and updating – Example: retrieving the transcript, changing sections, creating a new course, etc

21. A REAL LIFE example Requirements definition and analysis – Identifying business rules and needs Conceptual design – A model of the requirements to be able to transform it into a database implementation

22. A REAL LIFE example Logical design – Expression of the model in a DBMS software implementation Physical design – Specifications for physical storage and access of the database

23. The database approach File-processing system vs. database system File Processing SystemDatabase System Each user defines and implements the files needed for the application A data repository is defined once then accessed by various users Each application is free to name data elements independently The names and labels of data are defined one

24. The database approach Self-describing nature of a database system – The database system does not just contain the database itself but even the database definition called meta-data – Should work with any number of database applications as long as the database definition is available

25. The database approach Insulation between programs and data, and data abstraction – DBMS access programs do not require changing all programs that access the database when a structural change happens (program-data independence)

26. The database approach Insulation between programs and data, and data abstraction – User application programs can operate on the data by invoking operations regardless of how the operation is implemented (program-operation independence) Operation is a function or method made up of – Interface which contains the name and parameters – Implementation which defines the operation

27. The database approach Insulation between programs and data, and data abstraction – Data abstraction Characteristic that allows program-data independence and program-operation independence Data model is a type of data abstraction – Hides storage and implementation details that are not of interest to most database users

28. The database approach Support of multiple views of the data – Although there is a single repository of data, only a subset of this data may be made available to a particular set of users A view is virtual data derived from the database but not explicitly stored

29. The database approach Sharing of data and multi-user transaction processing – Transaction An executing program or process that includes one or more database accesses such as reading or updating the database Needs to have concurrency control, isolation, and atomicity

30. The database approach Sharing of data and multi-user transaction processing – Concurrency control Ensures that several users trying to update the same data do so in a controlled manner – Isolation Ensures that each transaction appears to execute in isolation from other transactions – Atomicity Ensures that either all the database operations in a transaction are executed or none are.

31. The database actors Database administrators (DBA) – A chief administrator to oversee and manage the database, the DBMS, and other related software. – Responsible for: authorizing access to the database coordinating and monitoring its use, and acquiring software and hardware resources as needed. – Accountable for breach of security or poor system response time.

32. The database actors Database designers – Responsible for Identifying the data to be stored in the database Choosing appropriate structures to represent and store data Communicating to prospective database users to understand the requirements Creating a design that fits user requirements – Final database design must be capable of supporting the requirements of ALL user groups

33. The database actors End users – Casual end users Occasionally access the database May need different information every time Use sophisticated query language to specify their requests Typically management level

34. The database actors End users – Naïve or parametric end users Make up the sizeable portion of database end users Constantly querying and updating the database Use canned transaction – Standard types of queries and updates Examples: bank tellers, reservation clerks, cashiers

35. The database actors End users – Sophisticated end users Engineers, scientists, business analysts – Thoroughly familiarize themselves with the DBMS facilities to implement their applications

36. The database actors End users – Standalone users Maintain personal databases – Uses ready-made program packages that provide easy-to- use menu-based or graphics-cased interfaces.

37. The database actors End users UserLevel of DBMS expertise CasualMinimal Naïve or parametricMinimal SophisticatedVery high StandaloneProficient in using a specific software package

38. The database actors System analysts and application programmers – System analyst Determine the requirements of end users Develop specifications for canned transactions that meet these requirements – Application programmer Implement the specifications as programs Also tests, debugs, documents and maintains – Also known as software engineers/developers

39. Behind the scene Other personnel are associated with the design, development, and operation of the DBMS software itself and the system environment surrounding it They are instrumental in making the database system available to end users but do not use the database for their own purpose

40. Behind the scene DBMS system designers and implementers – Design and implement the DBMS modules and interfaces as a software package – Ensures that the DBMS can interface with operating systems and programming language compilers

41. Behind the scene Tool developers – Design and implement tools Tools are software packages that facilitate database modeling and design, database system design, and improved performance. – Often purchased separately

42. Behind the scene Operators and maintenance personnel – System administration personnel – Responsible for the actual running and maintenance of hardware and software environment for the database system

43. The DBMS Advantage Controlling redundancy – Redundancy is storing the same data multiple times which leads to Duplication of effort Waste of storage space Data inconsistency – Should allow controlled redundancy in some cases

44. The DBMS Advantage Restricting unauthorized access – A database system should have a security and authorization subsystem – Only certain people can be given privilege to access confidential data at different levels

45. The DBMS Advantage Providing persistent storage for program objects – Persistency Ability of data to survive even after the program is terminated to enable later access of other programs.

46. The DBMS Advantage Providing storage structures for efficient query processing – Indexes Data structures that allow efficient disk search – Buffering module Provided by the DBMS to maintain parts of the database in the main memory – Query processing and optimization module Enables the choosing of an efficient query execution plan based on existing storage structures

47. The DBMS Advantage Providing backup and recovery – The DBMS should have a recovery facility to Restore the database in a state before a system failure occurred Resume the transaction from the point where it was interrupted

48. The DBMS Advantage Providing multiple user interfaces – A DBMS should be able to provide: Query languages for casual users Programming language interfaces for application programmers Forms and command codes for parametric users Menu-driven interfaces and natural language interfaces for standalone users – Graphical user interface (GUI) can be forms-style or menu-style

49. The DBMS Advantage Representing complex relationships among data – The DBMS must have the capability to Represent complex relationships among the data Define new relationships as they arise Retrieve and update related data easily and efficiently

50. The DBMS Advantage Enforcing integrity constraints – Integrity constraints Rules that must hold for the data Example: data type, uniqueness of data – Some constraints can be specified to the DBMS and automatically enforced – Others can be checked by the update programs or the applications during data entry

51. The DBMS Advantage Permitting inferencing and actions using rules – Deductive database systems A DBMS which provides capabilities for defining deduction rules for inferencing new information from the stored database facts – Triggers A form of a rule activated by updates to the table, which results to operations on other tables, sending messages, etc.

52. The DBMS Advantage Permitting inferencing and actions using rules – Stored procedures Become a part of the overall database definition Invoked when conditions are met – Active database systems Provide active rules that can automatically initiate actions when certain events and conditions occur

53. The DBMS Advantage Some added advantages – Potential for enforcing standards – Reduced application development time – Flexibility – Availability of up-to-date information – Economies of scale

54. When NOT to use DBMS Database overhead costs – Initial investment in hardware, software, and training – Generality for defining and processing data – Overhead for providing security, concurrency control, recovery, and integrity functions

55. When NOT to use DBMS Circumstances where DBMS is not ideal – Simple, well-defined database applications NOT expected to change – Stringent, real-time requirements – No multiple-user access to data

56. When NOT to use DBMS Industries which do not use general-purpose DBMS – Computer-aided design (CAD) tools – Communication and switching systems – Geographical information systems (GIS)