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Introduction to database technology

Introduction to database technology. (Based on Chapters 1-2 in Fundamentals of Database Systems by Elmasri and Navathe, Ed. 4). 1 Basic Definitions 2 Example of a Database 3 Data Models 3A. History of data Models 3B. Network Data Model 3C. Hierarchical Data Model.

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Introduction to database technology

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  1. Introduction to database technology (Based on Chapters 1-2 in Fundamentals of Database Systems by Elmasri and Navathe, Ed. 4)

  2. 1 Basic Definitions 2 Example of a Database 3 Data Models 3A. History of data Models 3B. Network Data Model 3C. Hierarchical Data Model 4 Schemas versus Instances 5 DBMS Languages 6 DBMS Interfaces 7 DBMS Component Modules13 Database System Utilities 8 Classification of DBMSs outline Introduction to Database Systems

  3. 1名詞定義 • Database : • A collection of related data. • Data : • Known facts that can be recorded and have an implicit meaning. Introduction to Database Systems

  4. Database Management System (DBMS) : 資料庫管理系統 • A software package/ system to facilitate(幫忙) the creation and maintenance of a computerized database. Introduction to Database Systems

  5. Basic Definitions • Mini-world(給定資料庫一個應用範圍，一個應用名稱) • Some part of the real world about which data is stored in a database. • For example, student grades and transcripts at a university. • 會計系統 Introduction to Database Systems

  6. 2. Example of a Database(with a Conceptual Data Model) • Mini-world example: • Part of a UNIVERSITY environment. • Entities(實體,東西) • Relationships(關係) Introduction to Database Systems

  7. Some mini-world entities: • STUDENTs • COURSEs • SECTIONs (of COURSEs) • (academic) DEPARTMENTs • INSTRUCTORs Introduction to Database Systems

  8. 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 Introduction to Database Systems

  9. NOTE: • The above could be expressed in the ENTITY-RELATIONSHIP data model. Introduction to Database Systems

  10. 6. 名詞定義 • Data Model: （資料模式) • A set of concepts to describe the structure of a database, and certain constraints that the database should obey. (結構) Introduction to Database Systems

  11. Operations for specifying database retrievals and updates by referring to the concepts of the data model.(資料處理動作) Introduction to Database Systems

  12. Categories of data models:(以詳細程度區分) • Conceptual data models (概念模式) • (high-level, semantic語意) • Physical data models(實體模式,儲存模式) • (low-level, internal) • Implementation data models (建置模式) • (record-oriented) Introduction to Database Systems

  13. Conceptual data models: • Provide concepts that are close to the way many users perceive data. • ( Examples： entity-relationship or object-based data models.) Introduction to Database Systems

  14. Physical data models: • Provide concepts that describe details of how data is stored(儲存) in the computer. • storage structure • Access path(幫助存取的結構,索引) Introduction to Database Systems

  15. Implementation data models: • Also called logical data model • Provide concepts that fall between the above two, balancing user views with some computer storage details. Introduction to Database Systems

  16. 6A. HISTORY OF DATA MODELS • Relational Model(關連式) • Network Model(網路式) • Hierarchical Data Model(階層式) • Object-oriented Data Model(物件導向) • Object-Relational Model(物件關連式) Introduction to Database Systems

  17. Relational Model: • proposed in 1970 by E.F. Codd (IBM), first commercial system in 1981-82. • Now in several commercial products • ORACLE, • SQL Server • INFORMIX, DB2 • SYBASE, Introduction to Database Systems

  18. Network Model: • the first one to be implemented by Honeywell in 1964-65 • (IDS System). • Adopted heavily due to the support by CODASYL • (CODASYL - DBTG report of 1971). Introduction to Database Systems

  19. Hierarchical Data Model : • implemented in a joint effort by IBM and North American Rockwell around 1965. • Resulted in the IMS family of systems. • The most popular model. Introduction to Database Systems

  20. Object-oriented Data Models : • several models have been proposed for implementing in a database system. • One set comprises models of persistent O-O Programming Languages • such as C++ (e.g., in ObjectStore or VERSANT), • and Smalltalk (e.g., in GEMSTONE). • Additionally, systems like O2, ORION (at MCC - then ITASCA), IRIS (at H.P.- used in Open OODB). Introduction to Database Systems

  21. Object-Relational Models : • Most Recent Trend. • Exemplified(範例) in Uni-SQL systems,ORACLE Introduction to Database Systems

  22. 7. Schemas(綱要) versus Instances（個例) • Database Schema : • The description of a database. • Includes • descriptions of the database structure and • the constraints that should hold on the database. • Schema Diagram: • A diagrammatic display of (some aspects of) a database schema. Introduction to Database Systems

  23. Introduction to Database Systems

  24. Introduction to Database Systems

  25. Database Instance : • The actual data stored in a database at a particular moment in time . (儲存的資料) • Also called database state (or occurrence). Introduction to Database Systems

  26. Introduction to Database Systems

  27. 10. DBMS Languages • Data Definition Language (DDL) • Data Manipulation Language (DML) • Data Control Language (DCL) Introduction to Database Systems

  28. Data Definition Language (DDL): • Used by the DBA and database designers to specify the conceptual schema of a database. • In many DBMSs, the DDL is also used to define internal and external schemas (views). Introduction to Database Systems

  29. Data Manipulation Language (DML): • Used to specify database retrievals and updates. • DML commands (data sublanguage) can be embedded in a general-purpose programming language (host language), such as C, COBOL, PL/1 or PASCAL. • Alternatively, stand-alone DML commands can be applied directly (query language). Introduction to Database Systems

  30. 11. DBMS Interfaces • Stand-alone query language interfaces. • Programmer interfaces for embedding DML in programming languages: • Pre-compiler Approach(Embedded SQL) • Procedure (Subroutine) Call Approach(CLI) Introduction to Database Systems

  31. Interfaces for the DBA: • Creating accounts, granting authorizations • Setting system parameters • Changing schemas or access path Introduction to Database Systems

  32. Introduction to Database Systems

  33. 13. Database System Utilities • To perform certain functions such as: • Loading data stored in files into a database. • Backing up the database periodically on tape. • Reorganizing database file structures. • Report generation utilities. • Performance monitoring utilities. • Other functions, such as sorting , user monitoring , data compression , etc. Introduction to Database Systems

  34. Data dictionary / repository: • Used to store schema descriptions and other information such as design decisions, application program descriptions, user information, usage standards, etc. Introduction to Database Systems

  35. 14. 資料庫管理系統的分類 • Based on data model • Other classifications Introduction to Database Systems

  36. 根據資料模式: • Traditional: • Relational, • Network, • Hierarchical. • Object-Relational • Emerging: • XML. Introduction to Database Systems

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