PowerPoint PresentationChapter 9: Database SystemsDatabaseFigure 9.1 A file versus a database organizationFigure 9.2 The conceptual layers of a database implementationSchemasDatabase Management SystemsDatabase ModelsRelational Database ModelFigure 9.3 A relation containing employee informationRelational DesignImproving a Relational DesignFigure 9.4 A relation containing redundancyFigure 9.5 An employee database consisting of three relationsFigure 9.6 Finding the departments in which employee 23Y34 has workedFigure 9.7 A relation and a proposed decompositionRelational OperationsFigure 9.8 The SELECT operationFigure 9.9 The PROJECT operationFigure 9.10 The JOIN operationFigure 9.11 Another example of the JOIN operationFigure 9.12 An application of the JOIN operationStructured Query Language (SQL)SQL ExamplesSQL Examples (continued)Object-oriented DatabasesFigure 9.13 The associations between objects in an object-oriented databaseAdvantages of Object-oriented DatabasesMaintaining Database IntegrityMaintaining database integrity (continued)Sequential FilesFigure 9.14 The structure of a simple employee file implemented as a text fileFigure 9.15 A procedure for merging two sequential filesFigure 9.16 Applying the merge algorithm (Letters are used to represent entire records. The particular letter indicates the value of the record’s key field.)Indexed FilesFigure 9.17 Opening an indexed fileHashingFigure 9.18 Hashing the key field value 25X3Z to one of 41 bucketsFigure 9.19 The rudiments of a hashing systemCollisions in HashingData MiningData Mining StrategiesSocial Impact of Database TechnologyCopyright © 2012 Pearson Education, Inc. Computer Science: An OverviewEleventh Editionby J. Glenn BrookshearChapter 9:Database SystemsCopyright © 2012 Pearson Education, Inc. 0-2Chapter 9: Database Systems•9.1 Database Fundamentals•9.2 The Relational Model•9.3 Object-Oriented Databases•9.4 Maintaining Database Integrity•9.5 Traditional File Structures•9.6 Data Mining•9.7 Social Impact of Database TechnologyCopyright © 2012 Pearson Education, Inc. 0-3DatabaseA collection of data that is multidimensional in the sense that internal links between its entries make the information accessible from a variety of perspectivesCopyright © 2012 Pearson Education, Inc. 0-4Figure 9.1 A file versus a database organizationCopyright © 2012 Pearson Education, Inc. 0-5Figure 9.2 The conceptual layers of a database implementationCopyright © 2012 Pearson Education, Inc. 0-6Schemas•Schema: A description of the structure of an entire database, used by database software to maintain the database•Subschema: A description of only that portion of the database pertinent to a particular user’s needs, used to prevent sensitive data from being accessed by unauthorized personnelCopyright © 2012 Pearson Education, Inc. 0-7Database Management Systems•Database Management System (DBMS): A software layer that manipulates a database in response to requests from applications•Distributed Database: A database stored on multiple machines–DBMS will mask this organizational detail from its users•Data independence: The ability to change the organization of a database without changing the application software that uses itCopyright © 2012 Pearson Education, Inc. 0-8Database Models•Database model: A conceptual view of a database–Relational database model–Object-oriented database modelCopyright © 2012 Pearson Education, Inc. 0-9Relational Database Model•Relation: A rectangular table–Attribute: A column in the table–Tuple: A row in the tableCopyright © 2012 Pearson Education, Inc. 0-10Figure 9.3 A relation containing employee informationCopyright © 2012 Pearson Education, Inc. 0-11Relational Design•Avoid multiple concepts within one relation–Can lead to redundant data–Deleting a tuple could also delete necessary but unrelated informationCopyright © 2012 Pearson Education, Inc. 0-12Improving a Relational Design•Decomposition: Dividing the columns of a relation into two or more relations, duplicating those columns necessary to maintain relationships–Lossless or nonloss decomposition: A “correct” decomposition that does not lose any informationCopyright © 2012 Pearson Education, Inc. 0-13Figure 9.4 A relation containing redundancyCopyright © 2012 Pearson Education, Inc. 0-14Figure 9.5 An employee database consisting of three relationsCopyright © 2012 Pearson Education, Inc. 0-15Figure 9.6 Finding the departments in which employee 23Y34 has workedCopyright © 2012 Pearson Education, Inc. 0-16Figure 9.7 A relation and a proposed decompositionCopyright © 2012 Pearson Education, Inc. 0-17Relational Operations•Select: Choose rows•Project: Choose columns•Join: Assemble information from two or more relationsCopyright © 2012 Pearson Education, Inc. 0-18Figure 9.8 The SELECT operationCopyright © 2012 Pearson Education, Inc. 0-19Figure 9.9 The PROJECT operationCopyright © 2012 Pearson Education, Inc. 0-20Figure 9.10 The JOIN operationCopyright © 2012 Pearson Education, Inc. 0-21Figure 9.11 Another example of the JOIN operationCopyright © 2012 Pearson Education, Inc. 0-22Figure 9.12 An application of the JOIN operationCopyright © 2012 Pearson Education, Inc. 0-23Structured Query Language (SQL)•Operations to manipulate tuples–insert–update–delete–selectCopyright © 2012 Pearson Education, Inc. 0-24SQL Examples•select EmplId, Deptfrom ASSIGNMENT, JOBwhere ASSIGNMENT.JobId = JOB.JobId and ASSIGNMENT.TermData = “*”•insert into EMPLOYEEvalues (‘43212’, ‘Sue A. Burt’, ’33 Fair St.’, ‘444661111’)Copyright © 2012 Pearson Education, Inc. 0-25SQL Examples (continued)•delete from EMPLOYEEwhere Name = ‘G. Jerry Smith’•update EMPLOYEEset Address = ‘1812 Napoleon Ave.’where Name = ‘Joe E. Baker’Copyright © 2012 Pearson Education, Inc. 0-26Object-oriented Databases•Object-oriented Database: A database constructed by applying the object-oriented paradigm–Each entity stored as a persistent object–Relationships indicated by links between objects–DBMS maintains inter-object linksCopyright © 2012 Pearson Education, Inc. 0-27Figure 9.13 The associations between objects in an object-oriented databaseCopyright © 2012 Pearson Education, Inc. 0-28Advantages of Object-oriented Databases•Matches design paradigm of object-oriented applications•Intelligence can be built into attribute handlers•Can handle exotic data