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Ch. 1 데이터베이스시스템

Ch. 1 데이터베이스시스템. What to Learn. Database System Overview Entity-Relationship diagram Relational Data Model Structure & Constraints SQL language How to use Commercial DBMS ’ s MS Access MS SQL Server Normalization ( 정규화 ) Transaction & Concurrency ( 동시성 ). What to Learn.

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Ch. 1 데이터베이스시스템

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  1. Ch. 1데이터베이스시스템

  2. What to Learn • Database System Overview • Entity-Relationship diagram • Relational Data Model • Structure & Constraints • SQL language • How to use Commercial DBMS’s • MS Access • MS SQL Server • Normalization (정규화) • Transaction & Concurrency (동시성) 데이터베이스시스템

  3. What to Learn • Database and Database system • Modeling a real world • Conceptual Modeling • Data Modeling • Data Structuring • File processing system • Advantages of database system 데이터베이스시스템

  4. What is a database (1) • data numbers, characters, images or other outputs from devices to convert physical quantities into symbols, in a very broad sense 현실세계의 사물과 사건을 문자, 수치, 기호, 음성, 그림 등의 형태로 표현한 기록 (record) • information the result of processing, manipulating and organizing data in a way that adds to the knowledge of the person receiving it. 사용자에게 전달되어 의사결정 등에 유용하게 쓰이도록 가치 있는 형태로 변환된 뜻(meaning, interpretation) Information = Processing (Data) 데이터베이스시스템

  5. What is a database (2) • database a collection of persistent data that is used by the application systems of some given enterprise 체계적으로 저장되고 통합적으로 관리되는 데이터의 집합 (collection) • Textbook definition (p.13) 조직체의 응용시스템들이 공유해서 사용하는 운영데이터(operational data)들이 구조적으로 통합된 모임 (operational data means data from day-to-day operations. In these days we store all the necessary data in the database including decision support database, not just operational data) 데이터베이스시스템

  6. Database system • Database system computerized record–keeping system a computerized system whose overall purpose is to store information and to allow users to retrieve and update that information on demand. 데이터베이스 개념과 기술에 입각하여 데이터를 수집/저장/가공/제공하는 컴퓨터 응용시스템 • Database Management System (DBMS) A component of a database system Software that handles all access to the database 데이터베이스시스템

  7. Database system Information Processing Users DBMS Computer Database 데이터베이스시스템

  8. Real World E-R diagram conceptual modeling conceptual world data modeling system boundary logical schema data structuring computer world physical schema stored database Modeling of the Real World 데이터베이스시스템

  9. Conceptual modeling • System boundary only the data we are interested in • Entity any distinguishable object that is to be represented in the database e.g. book, student, department • Relationship an association among entities 데이터베이스시스템

  10. publish loan Publisher Book Student title belong purchase loan date author Seller return date ISBN Department purchase date E-R diagram • Attributes (properties 속성) Items we describe (express) entities or relationships with • From the view of a database, entities and relationships are the same both of them are represented as tables 데이터베이스시스템

  11. Data Modeling • Data model an abstract, self-contained, logical definition of the objects, operators, constraints, and so forth, that together constitute the abstract machine 가상의 컴퓨터에서 데이터 객체들의 구조, 연산, 제약조건들을 명시한 정의 • Data models differ in structure, operators, constraints 데이터베이스시스템

  12. 회사 부서1 부서1 프로젝트1 프로젝트2 프로젝트3 사원1 사원2 사원3 사원4 사원5 hierarchical data model (p.35) • pre-relational, tree-structure, use pointers • a node has only one parent node • What if an employee works for two projects 데이터베이스시스템

  13. 대학 학과1 학과2 과목1 과목2 과목3 학생1 학생2 학생3 학생4 학생5 network data model (p.36) • pre-relational, use pointers • a node can have more than one parent node 데이터베이스시스템

  14. relational data model • Student table • The data is perceived by the user as tables (and nothing but tables) 데이터베이스의 논리적 구조가 relation 즉, 테이블의 집합으로 표현되는 데이터 모델 relation is a mathematical term for a table 데이터베이스시스템

  15. Other data model • Object-oriented data model from the OOP (object oriented programming)use pointers • Object/Relational data model hybrid of OODB & RDB 데이터베이스시스템

  16. Data Structuring • Physical representation of data • Consider file structure • indexing 데이터베이스시스템

  17. file processing system vs. database system • What is file processing system • Which is easier to use? • Problems of file processing system 1. data incompatiblity 2. data redundancy 3. data dependency 데이터베이스시스템

  18. example of problems Product1 (Prod_No, Prod_Name, price,monthlysales) Product2 (Prod_No, Prod_Name, cost, monthlyproduction) • Product1 is sorted by Prod_No, while Product2 is sorted by Prod_Name • Sales department & production department use different names for the same product. • Prod_Name’s are used twice • If the cost is inserted in Product1, application program that used Product1 should be changed. 데이터베이스시스템

  19. Data in the database system • Shared by multi-users • Integrated in a single database • Above characteristic requires • Standardization (표준화) • Concurrency control (동시성 제어) • Integrity (무결성) • Security (보안성) 데이터베이스시스템

  20. Advantages of database systems • The data can be shared • Redundancy and Incompatibility can be reduced • Transaction support can be provided (Transaction Commit or Rollback) • Integrity can be maintained • Security can be enforced • Standards can be enforced • Conflicting requirements can be balanced 데이터베이스시스템

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