Chapter01 introduction

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  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy Let us consider the case of a retail store that is trying to increase sales. Some of the data available includes sales levels for the last 36 months, advertising expenses, and customer comments from surveys. By itself, this data may be interesting, but it must be organized and analyzed to be useful in making a decision. For example, a manager might use economic and marketing models to forecast patterns and determine relationships among various advertising expenses and sales. The resulting information (presented in equations, charts, and tables) would clarify relationships among the data and would be used to decide how to proceed It requires knowledge to determine how to analyze data and make decisions.
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy A database management system (DBMS) is a collection of programs that enables users to create and maintain a database. The DBMS is hence a general-purpose software system that facilitates the processes of defining, constructing, and manipulating databases for various applications. Defining a database involves specifying the data types, structures, and constraints for the data to be stored in the database. Constructing the database is the process of storing the data itself on some storage medium that is controlled by the DBMS. Manipulating a database includes such functions as querying the database to retrieve specific data, updating the database to reflect changes in the miniworld, and generating reports from the data It is not necessary to use general-purpose DBMS software to implement a computerized database. We could write our own set of programs to create and maintain the database, in effect creating our own special-purpose DBMS software. In either case—whether we use a general-purpose DBMS or not—we usually have to employ a considerable amount of software to manipulate the database. We will call the database and DBMS software together a database system.
  • Lecture by Mr. Prum Chan Samedy Metadata is used to facilitate the understanding, characteristics, and management usage of data. The metadata required for effective data management varies with the type of data and context of use. In a library, where the data is the content of the titles stocked, metadata about a title would typically include a description of the content, the author, the publication date and the physical location. Examples of Metadata Camera In the context of a camera, where the data is the photographic image, metadata would typically include the date the photograph was taken and details of the camera settings (lens, focal length, aperture, shutter timing, white balance, etc.). Digital Music Player On a digital portable music player, the album names, song titles and album art embedded in the music files are used to generate the artist and song listings, and are considered the metadata. Information system In the context of an information system, where the data is the content of the computer files, metadata about an individual data item would typically include the name of the field and its length. Metadata about a collection of data items, a computer file, might typically include the name of the file, the type of file and the name of the data administrator.
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy For a small personal database, one person typically defines, constructs, and manipulates the database. However, many persons are involved in the design, use, and maintenance of a large database with a few hundred users.
  • Lecture by Mr. Prum Chan Samedy In this section we identify the people whose jobs involve the day-to-day use of a large database; we call them the "actors on the scene. Database Administrator: In any organization where many persons use the same resources, there is a need for a chief administrator to oversee and manage these resources. In a database environment, the primary resource is the database itself and the secondary resource is the DBMS and related software. Administering these resources is the responsibility of the database administrator (DBA). The DBA is responsible for authorizing access to the database, for coordinating and monitoring its use, and for acquiring software and hardware resources as needed. The DBA is accountable for problems such as breach of security or poor system response time. In large organizations, the DBA is assisted by a staff that helps carry out these functions. Database Designer: Database designers are responsible for identifying the data to be stored in the database and for choosing appropriate structures to represent and store this data. These tasks are mostly undertaken before the database is actually implemented and populated with data. It is the responsibility of database designers to communicate with all prospective database users, in order to understand their requirements, and to come up with a design that meets these requirements. In many cases, the designers are on the staff of the DBA and may be assigned other staff responsibilities after the database design is completed.
  • Lecture by Mr. Prum Chan Samedy Database designers typically interact with each potential group of users and develop a view of the database that meets the data and processing requirements of this group. These views are then analyzed and integrated with the views of other user groups. The final database design must be capable of supporting the requirements of all user groups. End user: The person that use the database for querying, updating, generating information, etc. System Analysts and Application Programmers (Software Engineers) System analysts determine the requirements of end users, especially naive and parametric end users, and develop specifications for canned transactions that meet these requirements. Application programmers implement these specifications as programs; then they test, debug, document, and maintain these canned transactions. Such analysts and programmers (nowadays called software engineers ) should be familiar with the full range of capabilities provided by the DBMS to accomplish their tasks.
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy The three-tier system adds middleware, which provide a way for clients of one DBMS to access data from another DBM. Figure in slide 48,49 and this slide illustrates the difference between single-tier, two-tier and three-tier software system
  • Lecture by Mr. Prum Chan Samedy
  • Lecture by Mr. Prum Chan Samedy Then we presented a list of capabilities that should be provided by the DBMS software to the DBA, database designers, and users to help them design, administer, and use a database: • Controlling redundancy. • Restricting unauthorized access. • Providing persistent storage for program objects and data structures. • Permitting inferencing and actions by using rules. • Providing multiple user interfaces. • Representing complex relationships among data. • Enforcing integrity constraints. • Providing backup and recovery.
  • Chapter01 introduction

    1. 1. Database SystemLecturer: Mr. Prum Chan Samedy,MScITTel: 012 456-896E-mail: chan_samedy@yahoo.com Bachelor of Science in Information Technology
    2. 2. Objectives After finished this course students able to design to manage large bodies of information. Management of data involves both designing structure for storage of information and providing mechanisms for the manipulation of information. Data Management – Build an Entity-Relationship model for a relational DBMS – Implement the database in MS Access/SQL Server – Normalize tables – Produce SQL coding to manage data Application Development – Plan and design an application system – Implement an application in MS AccessDatabase system 2
    3. 3. Class References  Fundamental of Database systems, Elmasri & NavattheDatabase system 3
    4. 4. Database System Chapter 1: Introduction Databases and Database usersDatabase system 4
    5. 5. Outline  Basic Definitions  Typical DBMS Functionality  Example of a Database (UNIVERSITY)  Advantages of Using the Database Approach  Database UsersDatabase system 5
    6. 6. Basic Definitions- Data VS Information DATA: Facts concerning people, objects, vents or other entities. Databases store data. INFORMATION: Data presented in a form suitable for interpretation. Data is converted into information by programs and queries.Database system Figure 1.1 Input-process-output 6
    7. 7. Example of DataDatabase system 7
    8. 8. Why every employees in company need information? Shopping in supermarketDatabase system
    9. 9. Basic Definitions – Database VS DBMS DATABASE: DATABASE MANAGEMENT SYSTEM (DBMS) : A software system that enables users to define, create, and maintain the database and that provides controlled access to this database.Database system 9
    10. 10. Basic Definitions – Database System  DATABASE SYSTEM: Database System =DBMS+Database The DBMS software together with the data itself. Sometimes, the applications are also included. Oracle, SQL Server,DB2, MySQL, Infomix,…Database system
    11. 11. Basic Definitions – Metadata  Metadata “Data about data”  Description of fields Display and format instructions Structure of files and tables Security and access rules Triggers and operational rules Example of MetadataDatabase system 11
    12. 12. Basic Definitions –Sample of Metadata Sample of MetadataDatabase system 12
    13. 13. Simplified database system environment A simplified database system environmentDatabase system 13
    14. 14. Database application programA software program that interacts with the database by issuing an appropriate request (typically an SQL statement) to the DBMS.Database system
    15. 15. Database Overview- Why Use a DBMS?  Using a DBMS to manage data has many advantages: – Data independence – Sharing of data among multiple applications – Data integrity and security – Concurrent access and crash recovery – Data administration – Reduced application development timeDatabase system
    16. 16. Database Users-1  Users may be divided into – Those who actually use and control the database content, and those who design, develop and maintain database applications (called “Actors on the Scene”), and – Those who design and develop the DBMS software and related tools, and the computer systems operators (called “Workers Behind the Scene”).Database system 16
    17. 17. Database Users-2  Actors on the scene – Database administrators:  Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations. – Database Designers/Ananyst:  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.Database system 17
    18. 18. Database Users-3  Application programmer/Application Developer They access the data from programs written in high-level language such as Visual basic or C+ +,C#, Java. The application programmers design systems such as payroll, Inventory, and billing.  End user They use the data for queries, reports and some of them update the database content.Database system 18
    19. 19. Exercise 1.1 Indicate which type of user would perform the following functions for a payroll system in a large company: A. Write an application program to generate and print the checks. B. Change the address in the database for an employee who has moved. C. Create a new user account for a newly hired payroll clerkDatabase system 19
    20. 20. RDBMS  Relational Database Management System (RDBMS) – Relational Database is a collection of relations (table) Oracle, SQL Server, DB2, My SQL,… User tables Data dictionaryDatabase system 20
    21. 21. Sample of Relational Database Index 199011913 19959999 19860001 19901913 19911123 19959999 [EMPLOYEE table] colum Index nHire_ Serial_ [DEPARTMENT table] Emp_Name Salary Dept_NoYear No Dept_No Department Area1990 1913 Pich Oudam 180000 5648 Row 5648 Systems P.P Prum Chan Dara 4327 Personnel KD1987 0042 200000 4327 2271 General affairs KP1992 7699 Keo Rithy 190000 2271 0381 Sales KK . . . . . . . . . . . . . . . . . . . . . . . . FieldDatabase system 21
    22. 22. Database Architecture  Single tier Architecture  Two-tier Architecture  Three-tier ArchitectureDatabase system 22
    23. 23. Single tier a. Single tier: DBMS All on one machine Software Access by terminals DatabaseDatabase system 23
    24. 24. Client/Server (Two tier )Front-End/Client b. Two-Tier: Application #1 Server with many clients Application #2 DBMS Database Server containing Software centralized shared data Application #3 DBMS manages data resources like an operating system manages hardware resourcesDatabase system 24
    25. 25. Three-tier architecture Front-End/Client Front-End/Client Application Application #3 #1 DBMS I DBMS II Server Server Software Software Middleware Applicatio4 Application #3 #2 Database Database c. Three-tier: Two kings of DBMS Connected by MiddlewareDatabase system 25
    26. 26. Three-tier architecture Also call Distributed Systems Solutions are distributed between client PC’s and one or more servers.Database system
    27. 27. Exercise 1.2 Specify whether each system would be single-tiered, two- tiered, or three-tiered. a. The Happy Nights motel chain allows local managers to purchase a franchise. They can install and use the DBMS of their choice for their reservation system. The only requirement is that they be able to connect and communicate with the central office’s system. b. The Sticky Wicket Company has home offices in Detroit and branches in Chicago and Baltimore. The inventory and parts database is distributed with each branch keeping its own inventory. One central DBMS located in Detroit allows instant ordering of supplies through the central office.Database system 27
    28. 28. Database system 28

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