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Database Systems

Database Systems. 高海昌 hchgao@xidian.edu.cn. Major Content & Grade. Introduction * The Relational Model *** SQL **** Transaction Management *** Database Design (E-R) *** Database Design (Normalization) *** 考核方式 笔试(70%)+平时 ( 课堂 / 作业 / 上机 ) ( 30%). Books. Book

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Database Systems

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  1. Database Systems 高海昌 hchgao@xidian.edu.cn

  2. Major Content & Grade • Introduction * • The Relational Model *** • SQL **** • Transaction Management *** • Database Design (E-R) *** • Database Design (Normalization) *** • 考核方式 笔试(70%)+平时(课堂/作业/上机) (30%)

  3. Books • Book • Abraham Silberschatz, Henry F. Korth, S.Sudarshan, Database System Concepts (5th ed.), The McGraw-Hill Companies, 2006 • Reference Books • Thomas M. Connolly, et al. Database Systems: A practical approach to Design, Implementation, and Management. 4th edition, Addison-Wesley, 2008 • 萨师煊，王珊 《数据库系统概论》 高等教育出版社 (第4版)

  4. Unit 1 Introduction • Data & Database • DBMS • Database System • Database Applications • Brief History of Data Management

  5. Data & Database • How to management Information (Data)? • data: data are raw facts that describe people, objects, and events.

  6. Data & Database • How to management Information(Data)? • Database :An integrated collection of related data constitutes a Database (DB).

  7. Application1 Database Application2 DBMS …… DBMS • Database Management System (DBMS) : Contains information about a particular enterprise • Collection of interrelated data • Set of programs to access the data • An environment that is both convenient and efficientto use

  8. DBMS • What should A DBMS needed? • Data can be shared • Redundancy(冗余) can be reduced • Inconsistency(不一致性) can be avoided • Transaction(事务) support can be provided • Integrity(完整性) can be maintained • Security(安全性) can be enforced • Conflicting(冲突) requirements can be balanced • Standards can be enforced DBMS is less complex than OS.

  9. DBMS Architecture • 外模式（External Schema，也称子模式或用户模式） 　——数据库用户使用的局部数据的逻辑结构和特征的描述 • 模式（Logical Schema, Schema，也称逻辑模式） 　——数据库中全体数据的逻辑结构和特征（型）的描述 • 内模式（Physical Schema，也称存储模式） 　——数据物理结构和存储方式的描述

  10. DBMS Architecture • ANSI/SPARC architecture

  11. Functions of DBMS 1) Data definition(Data Definition Language—DDL) 利用DDL可方便地对数据库中的数据对象进行定义。 2) Data manipulation(Data Manipulation Language—DML) 用户利用DML实现对数据库数据的基本操作，如查询、插入、删除和修改等。 3) Database running management 在数据库的建立、运行和维护时，由DBMS进行统一管理、统一控制，以确保数据的安全性、完整性、多用户的并发操作及发生故障后的系统恢复。 4) Database establish and maintain 数据库初始数据的录入、转换功能、数据库的转储、恢复功能、数据库的重组织和性能监视、分析功能等。一般由DBMS中的一些实用程序完成。

  12. User User User Application Development Tools DBMS DBA OS DB Database System • Database System: A computerized record-keeping systems, composed byData, Hardware, Software and People

  13. Components of Database System • Data • Anything that is of significance to the individual or organization concerned • Two characters integrated - needn’t include redundant information shared – a record file should be shared by different user • Multi-views • Hardware • Secondary storage volume I/O device, Device controller, I/O channel, etc • Processor and Main memory

  14. Components of Database System • Software • OS Unix，Linux, OS/2, Windows NT … • Database Management System Oracle, DB2, Sybase, MySQL, PostgreSQL, … • Others software utilities, application development tools, designs aid, report writer, transaction manager

  15. Components of Database System • People • End users—Interactive users. • Casual users (临时用户):facility with SQL… • Naive users (初级用户): bank clerks… • Application programmers • An application programmer, in the sense used with DBMS, writes the menu applications used by naive users. • DBA (database administrator) • A DBA is a computer professional responsible for the design and maintenance of the database.

  16. 题外：数据库领域的三位图灵奖得主 • Charles W. Bachman(查尔斯 • 巴赫曼)　1973 • 主持设计与开发了最早的网状数据库管理系统IDS，它的设计思想和技术直接影响了后来的数据库。他还促成了数据库标准的制定，即DDL和DML规范说明。 • Edgar F. Codd(埃德加 • 科德)　1981 • 于1970年6月发表了题为“A Relational Model of 　Data for Large Shared Data Banks”一文，首次 　明确而清晰地为数据库系统提出了一种崭新的模 　型，即关系模型。一经提出迅速商品化。 • James Gray(詹姆斯 • 格雷)　1998 • 在事务处理技术上的创造性思维和开拓性工作， 　使他成为该技术领域公认的权威。在解决保障 　数据的完整性、安全性、并行性，以及从故障 　中恢复方面发挥了十分关键的作用。

  17. Unit 1 Introduction • Data & Database • DBMS • Database System • Database Applications • Brief History of Data Management

  18. Database Applications Database contains information about a particular enterprise. • Database Applications: • Banking: all transactions • Airlines: reservations, schedules • Universities: registration, grades • Sales: customers, products, purchases • Manufacturing: production, inventory, orders, supply chain • Human resources: employee records, salaries, tax deductions • …… Databases touch all aspects of our lives

  19. Database Applications Architecture • Client/Server architecture

  20. Database Applications Architecture • Browser/Server architecture

  21. File1 Prog1 File System File2 Prog2 Filen Progn Brief History of Data Management • In the early days(Before 1960s), database applications were built on top of FILE systems

  22. Brief History of Data Management • Drawbacks of using FILE SYSTEMS : • Data redundancyand inconsistency(不一致性) • Difficulty in accessing data • Data isolation • Integrityproblems • Atomicity of updates • Concurrent access by multiple users • Security problems It’s impossible to programmers for even ONE solution!

  23. DB Prog1 DBMS Prog2 Progn Brief History of Data Management • Management using DBMS • Database systems offer solutions to all the above problems in using file systems !

  24. R1 R2 R3 R4 R5 History of Database System • Hierarchical system (1960s) • IBM’s IMS • data represent to user is the form of tree structure • IMS provided the hierarchical data model, where different kinds of records relate to one another in a hierarchical form. • data shared by several applications

  25. Example of Hierarchical system 学院 教研室 教师 • 用指针实现记录间的联系！

  26. History of Database System • Network System (1960s) • Cullinet Software IDMS (CODASYL DBTG Report) • The network data model, a generalization of the hierarchical model where a set of record in one layer might have two different containing hierarchies at the next layer up. • data represent to user is graph structure • operator similar to hierarchical system Bachman

  27. S SC C S001 李小明 CS S001 C01 80 C01 高等数学 3 S002 张娜 CS S001 C02 78 C02 计算机原理 4 S003 王杰 CS S002 C01 65 …… …… … …… …… … S002 C02 84 S003 C01 91 S003 C02 85 …… ….. …… Example of Network System

  28. History of Database System • Relational system (1970s) • data representation are table, operator generate new tables from old tables • In a relational database, all information is represented in the form of named tables (relation) with labeled column (attribute) • In the relational model, a column of a table must contain a single, unstructured value(first normal form rule) • Products : SQL server, Oracle, Sybase, DB2, Informix, Ingres, etc. Codd

  29. Example of Relational System enrollment (注册) students courses

  30. History of Database System • Object-Relational system (1980s) • In an object-relational database, information is still represented as in the relational model in the form of named tables with labeled columns • but the column values are no longer restricted by the First Normal Form rule (can be STRUCT or SET datatype).

  31. Example of ORDBMS students courses

  32. History of Database System • 1990s: • Large decision support and data-mining applications • Large multi-terabyte data warehouses • Emergence of Web commerce • 2000s: • XML and XQuery standards • Automated database administration

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