北郵數(shù)據(jù)庫第一章課件

1、DataBase System ConceptsDataBase System ConceptsDeng Fang DDataBase System ConceptsIntroduction Book: Database System Concepts Teaching hours: total 68 hours, includinglecture time: 48 hourspractice time: 16 hoursDataBase System ConceptsReference Book:數(shù)據(jù)庫系統(tǒng)概念數(shù)據(jù)庫系統(tǒng)概念 機械工業(yè)出版社機械工業(yè)出版社數(shù)據(jù)庫系統(tǒng)概論，王珊著，高等教育出版社

2、數(shù)據(jù)庫系統(tǒng)概論，王珊著，高等教育出版社數(shù)據(jù)庫系統(tǒng)原理，李建中，王珊編著，電子工業(yè)出版社數(shù)據(jù)庫系統(tǒng)原理，李建中，王珊編著，電子工業(yè)出版社DataBase System ConceptsContents(1)Part 1 IntroductionDatabase Structure, Language, Users, Data ModelPart 2 Relational DatabasesRelational ModelSQLIntegrity and SecurityPart 3 Database DesignE_R ModelRelational-database DesignDataBas

3、e System ConceptsContents(2)Part 4 Data Storage and QueryingStorage and File StructureIndexing and HashingQuerying ProcessingQuery Optimization Part 5 Transaction ManagementTransactionsConcurrency controlRecovery System DataBase System ConceptsContents(3)Part 6 Database System ArchitecturePart 7 Obj

4、ect-Based Databases and XMLPart 8 Case StudiesPart 9 Other TopicsDataBase System ConceptsIntroductionChapter One Introductionn History of Database systemsn What is Database systems n Three levels and Data Abstractionn Data Modelsn Database languagesn Database usersn Database system structureDataBase

5、 System ConceptsHistory of Database systemsDevelopment of Data ManagementManual ModelApplication Program1Application Program2Application ProgramnData Set1Data Set2Data SetnDataBase System ConceptsHistory of Database systemsFile System Application Program1Application Program2Application ProgramnData

6、Set1Data Set2Data SetnFile SystemDataBase System ConceptsHistory of Database systemsDrawbacks of using file systems to store Data:Data redundancy and inconsistencyMultiple file formats, duplication of information in different filesDifficulty in accessing data Need to write a new program to carry out

7、 each new taskData isolation multiple files and formatsIntegrity problemsIntegrity constraints (e.g. account balance 0) become part of program codeHard to add new constraints or change existing onesAtomicity of updatesConcurrent access by multiple usersSecurity problemsDataBase System ConceptsHistor

8、y of Database systemsDataBase System ConceptsHistory of Database systemsDatabase SystemDBMSApplication Program1Application Program2Application ProgramnDatabaseDataBase System ConceptsBenefits of Database Approach Data can be shared; Redundancy can be reduced; Inconsistency can be avoided(to some ext

9、ent); Transaction support can be provided; Integrity can be maintained; Security can be enforced; DataBase System ConceptsDatabase System Vs File systemFile systemData ManagementApp.App.File SystemApp.Data ManagementApp.Data Management 1950s and early 1960s: Data processing using magnetic tapes for

10、storage Punched cards for input Late 1960s and 1970s: Hard disks allow direct access to data Network and hierarchical data models in widespread use Ted Codd defines the relational data model Would win the ACM Turing Award for this work IBM Research begins System R prototype UC Berkeley begins Ingres

11、 prototype High-performance (for the era) transaction processingDataBase System ConceptsHistory of Database systems 1980s: Research relational prototypes evolve into commercial systems SQL becomes industrial standard Parallel and distributed database systems Object-oriented database systems 1990s: L

12、arge decision support and data-mining applications Large multi-terabyte data warehouses Emergence of Web commerce 2000s: XML and XQuery standards Automated database administrationDataBase System ConceptsHistory of Database systemsDataBase System ConceptsHistory of Database systems1968, IBMs IMS (Inf

13、ormation Management system)hierarchical data model;1970s, Cullinet Softwares IDMS1971, CODASYL(Conference on Data System Language) report network data model;1970, E.F.Codd defined the relational model1990s, object-relational database, WEB database, parallel databaseDataBase System ConceptsWhat is Da

14、tabase systemsDBMS: DataBase Management SystemDB: databasea collection of interrelated dataApplications Set of programs to access the dataDBMS(教材上） contains information about a particular enterpriseCollection of interrelated dataSet of programs to access the data An environment that is both convenie

15、nt and efficient to useDataBase System ConceptsWhat is Database systemsDataBase System ConceptsDatabase Applications:Banking: all transactionsAirlines: reservations, schedulesUniversities: registration, gradesSales: customers, products, purchasesManufacturing: production, inventory, orders, supply c

16、hainHuman resources: employee records, salaries, tax deductionsDatabases touch all aspects of our livesDatabase ApplicationsDataBase System ConceptsThree level Architecturedescribes how a record is physically stored.describes logical data stored in database, and the relationships among the data. Com

17、munity user viewPart of entire databaseIndividual user viewsPhysical abstractionLogical abstractionView abstraction Physical level: describes how a record (e.g., customer) is stored. Logical level: describes data stored in database, and the relationships among the data.type customer = recordcustomer

18、_id : string; customer_name : string;customer_street : string;customer_city : integer;end; View level: Part of the entire database. Application programs hide details of data types. Views can also hide information (such as an employees salary) for security purposes. DataBase System ConceptsDataBase S

19、ystem ConceptsData AbstractionView abstraction Logical abstraction Physical abstractionDataBase System ConceptsMappings（映象）（映象） The Physical(internal)/Logical(conceptual) mappingdefines the correspondence between the logical view and the stored database;specifies how logical records and fields are r

20、epresented at the physical level; The View(external)/Logical(conceptual) mappingdefines the correspondence between a particular view and the logical view;DataBase System ConceptsData Independence Physical Data Independence （物理數(shù)據(jù)獨立性） the ability to modify the physical schema without changing the logi

21、cal schema or the views(The Physical(internal)/Logical(conceptual) mapping)Application programs need not be rewritten if the physical schema changes. Logical Data Independence （邏輯數(shù)據(jù)獨立性） the ability to modify the logical schema without changing the logical views(The View(external)/Logical(conceptual)

22、 mapping)主語言主語言+DML用戶用戶A1主語言主語言+DML用戶用戶A2主語言主語言+DML用戶用戶B1主語言主語言+DML用戶用戶B2主語言主語言+DML用戶用戶B3外模式外模式A外模式外模式B概念模式概念模式外模式外模式/模式映象模式映象A外模式外模式/模式映象模式映象B模式模式/內(nèi)模式映象內(nèi)模式映象內(nèi)模式內(nèi)模式數(shù)據(jù)庫數(shù)據(jù)庫由數(shù)據(jù)庫由數(shù)據(jù)庫管理員建管理員建立和維護立和維護OSDBMS數(shù)據(jù)庫系統(tǒng)的體系結(jié)構(gòu)數(shù)據(jù)庫系統(tǒng)的體系結(jié)構(gòu)DataBase System ConceptsSchema （模式） the description of the structure of the data

23、 in a database e.g., the database consists of information about a set of customers and accounts and the relationship between them);Analogous to type information of a variable in a program;Physical schema: database design at the physical level;Logical schema: database design at the logical level;Inst

24、ance（實例）（實例） the actual content of the database at a particular point in time Analogous to the value of a variableDataBase System ConceptsData ModelsA collection of conceptual tools for describing data, data relationships,data semantics ,and consistency constrains.Data Structure;Data Operations;Cons

25、traint Rules.DataBase System ConceptsData ModelsObject_based data model:Entity-Relational Model (E_R Model);Object-oriented Model;Record_based data model:hierarchical data model;network data model;relational data modelDataBase System Conceptscustomer-nameCustomer-idcustomer-streetcustomer-cityaccoun

26、t-numberJohnsonSmithJohnsonJonesSmith192-83-7465019-28-3746192-83-7465321-12-3123019-28-3746AlmaNorthAlmaMainNorthPalo AltoRyePalo AltoHarrisonRyeA-101A-215A-201A-217A-201Relational Data ModelDataBase System ConceptsDatabase LanguagesData Definition Language (DDL):Specification notation for defining

27、 the database schema; Eg:Create table account ( account-number char(10), balance integer)Including:Database schema Data storage and definition language DataBase System ConceptsDatabase LanguagesLanguage for accessing and manipulating the data organized by the appropriate data model;( query, insert ,

28、 delete, update )DML also known as query languageTwo classes of languages Procedural user specifies what data is required and how to get those data ;Nonprocedural user specifies what data is required without specifying how to get those data;SQL is the most widely used query languageDataBase System C

29、onceptsUsers are differentiated by the way they expect to interact with the systemApplication programmers interact with system through DML callsSophisticated users form requests in a database query languageSpecialized users write specialized database applications that do not fit into the traditional

30、 data processing frameworkNaive users invoke one of the permanent application programs that have been written previouslyE.g. people accessing database over the web, bank tellers, clerical staffDataBase System Concepts End Users: naive Userscasual users -Interactive SQL Application Programmers-Proced

31、ural SQL,Transaction Database analyzer and designer -Data modeling, Normalization theory, Database Administrators, DBA -Database maintenance , Security , Integrity,Recovery Database Management System designer and implementer -Implementation technique of above techniques for Special and New Database

32、Management SystemDataBase System ConceptsCoordinates all the activities of the database system; the database administrator has a good understanding of the enterprises information resources and needs.Database administrators duties include:Schema definitionStorage structure and access method definitio

33、nSchema and physical organization modificationGranting user authority to access the databaseSpecifying integrity constraintsActing as liaison with usersMonitoring performance and responding to changes in requirementsDBADataBase System ConceptsDatabase System StructureDataBase System ConceptsDatabase

34、 System StructureStorage manager is a program module that provides the interface between the low-level data stored in the database and the application programs and queries submitted to the system.is responsible for efficient storing, retrieving and updating of data;Authorization and integrity manager;Transaction manager;File manager;Buff