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

2. Introduction to Database Systems2 outline 1Basic Definitions 2Example of a Database 3Data Models 3A. History of data Models 3B. Network Data Model 3C. Hierarchical Data Model 1Basic Definitions 2Example of a Database 3Data Models 3A. History of data Models 3B. Network Data Model 3C. Hierarchical Data Model 4Schemas versus Instances 5DBMS Languages 6DBMS Interfaces 7 DBMS Component Modules 8 Database System Utilities 9Classification of DBMSs 4Schemas versus Instances 5DBMS Languages 6DBMS Interfaces 7 DBMS Component Modules 8 Database System Utilities 9Classification of DBMSs

3. Introduction to Database Systems3 1 名詞定義 Database : A collection of related data. Data : Known facts that can be recorded and have an implicit meaning.

4. Introduction to Database Systems4 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.

5. Introduction to Database Systems5 Database System : ( 資料庫系統 ) The DBMS software together with the data itself. Sometimes, the applications are also included. Database System = Data + DBMS + (Program) Database System = Data + DBMS + (Program)

6. Introduction to Database Systems6 INSERT FIGURE 1.1

7. Introduction to Database Systems7 Basic Definitions Mini-world( 給定資料庫一個應用範圍 ) Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university.

8. Introduction to Database Systems8 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 )

9. Introduction to Database Systems9 Some mini-world entities: STUDENTs COURSEs SECTIONs (of COURSEs) (academic) DEPARTMENTs INSTRUCTORs

10. Introduction to Database Systems10 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

11. Introduction to Database Systems11 NOTE: The above could be expressed in the ENTITY-RELATIONSHIP data model.

12. Introduction to Database Systems12 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 ) 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 )

13. Introduction to Database Systems13 Operations for specifying database retrievals and updates by referring to the concepts of the data model.( 資料處理動作 )

14. Introduction to Database Systems14 Categories of data models: 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)

15. Introduction to Database Systems15 Conceptual data models: Provide concepts that are close to the way many users perceive data. ( Examples ： entity-relationship or object-based data models.)

16. Introduction to Database Systems16 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 )

17. Introduction to Database Systems17 Implementation data models: Also called logical data model Provide concepts that fall between the above two, balancing user views with some computer storage details.

18. Introduction to Database Systems18 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 )

19. Introduction to Database Systems19 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,

20. Introduction to Database Systems20 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).

21. Introduction to Database Systems21 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.

22. Introduction to Database Systems22 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).

23. Introduction to Database Systems23 Object-Relational Models : Most Recent Trend. Exemplified( 範例 ) in Uni-SQL systems,ORACLE

24. Introduction to Database Systems24 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.

25. Introduction to Database Systems25

26. Introduction to Database Systems26 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).

27. Introduction to Database Systems27

28. Introduction to Database Systems28 The database schema changes very infrequently. The database state changes every time the database is updated. Schema is also called intension, whereas state is called extension.

29. Introduction to Database Systems29 10. DBMS Languages Data Definition Language (DDL) Data Manipulation Language (DML) Data Control Language (DCL)

30. Introduction to Database Systems30 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).

31. Introduction to Database Systems31 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).

32. Introduction to Database Systems32 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)

33. Introduction to Database Systems33 Interfaces for the DBA: Creating accounts, granting authorizations Setting system parameters Changing schemas or access path

34. Introduction to Database Systems34

35. Introduction to Database Systems35 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.

36. Introduction to Database Systems36 Data dictionary / repository: Used to store schema descriptions and other information such as design decisions, application program descriptions, user information, usage standards, etc.

37. Introduction to Database Systems37 14. 資料庫管理系統的分類 Based on data model Other classifications

38. Introduction to Database Systems38 根據資料模式 : Traditional: Relational, Network, Hierarchical. Object-Relational Emerging: XML.

39. Introduction to Database Systems39 其他它分類 : Single-user (typically used with micro- computers) vs. multi-user (most DBMSs). Centralized (uses a single computer with one database) vs. distributed (uses multiple computers, multiple databases) Distributed Database Systems have now come to be known as client server based database systems because they do not support a totally distributed environment, but rather a set of database servers supporting a set of clients.

40. Introduction to Database Systems40 Distributed Database Systems have now come to be known as client server based database systems because they do not support a totally distributed environment, but rather a set of database servers supporting a set of clients.