PowerPoint PresentationChapter 1 OutlineIntroductionIntroduction (cont'd.)Slide 5Slide 6Slide 7Slide 8An ExampleAn Example (cont'd.)Slide 11Slide 12Slide 13Slide 14Slide 15Characteristics of the Database ApproachCharacteristics of the Database Approach (cont'd.)Self-Describing Nature of a Database SystemSlide 19Insulation Between Programs and DataData AbstractionSupport of Multiple Views of the DataSharing of Data and Multiuser Transaction ProcessingSharing of Data and Multiuser Transaction Processing (cont'd.)Database UsersDatabase Users (cont'd.)Slide 27Advantages of Using the DBMS ApproachAdvantages of Using the DBMS Approach (cont'd.)Slide 30Slide 31Slide 32When Not to Use a DBMSSummaryCopyright © 2011 Pearson Education, Inc. Publishing as Pearson Addison-WesleyChapter 1Databases and Database UsersCopyright © 2011 Ramez Elmasri and Shamkant NavatheChapter 1 OutlineIntroductionAn ExampleCharacteristics of the Database ApproachDatabase UsersAdvantages of Using the DBMS ApproachWhen Not to Use a DBMSCopyright © 2011 Ramez Elmasri and Shamkant NavatheIntroductionDatabase Collection of related dataKnown facts that can be recorded and that have implicit meaningMiniworld or universe of discourse (UoD)Represents some aspect of the real worldBuilt for a specific purposeCopyright © 2011 Ramez Elmasri and Shamkant NavatheIntroduction (cont'd.)Example of a large commercial databaseAmazon.comDatabase management system (DBMS) Collection of programs Enables users to create and maintain a databaseDefining a database Specify the data types, structures, and constraints of the data to be storedCopyright © 2011 Ramez Elmasri and Shamkant NavatheIntroduction (cont'd.)Meta-dataDatabase definition or descriptive information Stored by the DBMS in the form of a database catalog or dictionaryManipulating a databaseQuery and update the database miniworld Generate reportsCopyright © 2011 Ramez Elmasri and Shamkant NavatheIntroduction (cont'd.)Sharing a database Allow multiple users and programs to access the database simultaneouslyApplication program Accesses database by sending queries to DBMSQuery Causes some data to be retrievedCopyright © 2011 Ramez Elmasri and Shamkant NavatheIntroduction (cont'd.)Transaction May cause some data to be read and some data to be written into the databaseMaintain the database system Allow the system to evolve as requirements change over timeCopyright © 2011 Ramez Elmasri and Shamkant NavatheCopyright © 2011 Ramez Elmasri and Shamkant NavatheAn ExampleUNIVERSITY database Information concerning students, courses, and grades in a university environmentData recordsSTUDENT COURSESECTION GRADE_REPORT PREREQUISITECopyright © 2011 Ramez Elmasri and Shamkant NavatheAn Example (cont'd.)Specify structure of records of each file by specifying data type for each data element String of alphabetic charactersIntegerEtc.Copyright © 2011 Ramez Elmasri and Shamkant NavatheAn Example (cont'd.)Construct UNIVERSITY databaseStore data to represent each student, course, section, grade report, and prerequisite as a record in appropriate fileRelationships among the recordsManipulation involves querying and updatingCopyright © 2011 Ramez Elmasri and Shamkant NavatheAn Example (cont'd.)Examples of queries:Retrieve the transcriptList the names of students who took the section of the ‘Database’ course offered in fall 2008 and their grades in that sectionList the prerequisites of the ‘Database’ courseCopyright © 2011 Ramez Elmasri and Shamkant NavatheAn Example (cont'd.)Examples of updates:Change the class of ‘Smith’ to sophomoreCreate a new section for the ‘Database’ course for this semesterEnter a grade of ‘A’ for ‘Smith’ in the ‘Database’ section of last semesterCopyright © 2011 Ramez Elmasri and Shamkant NavatheAn Example (cont'd.)Phases for designing a database: Requirements specification and analysisConceptual designLogical design Physical designCopyright © 2011 Ramez Elmasri and Shamkant NavatheCopyright © 2011 Ramez Elmasri and Shamkant NavatheCharacteristics of the Database ApproachTraditional file processingEach user defines and implements the files needed for a specific software application Database approachSingle repository maintains data that is defined once and then accessed by various usersCopyright © 2011 Ramez Elmasri and Shamkant NavatheCharacteristics of the Database Approach (cont'd.)Main characteristics of database approach Self-describing nature of a database systemInsulation between programs and data, and data abstractionSupport of multiple views of the dataSharing of data and multiuser transaction processingCopyright © 2011 Ramez Elmasri and Shamkant NavatheSelf-Describing Nature of a Database SystemDatabase system contains complete definition of structure and constraintsMeta-dataDescribes structure of the databaseDatabase catalog used by: DBMS software Database users who need information about database structureCopyright © 2011 Ramez Elmasri and Shamkant NavatheCopyright © 2011 Ramez Elmasri and Shamkant NavatheInsulation Between Programs and DataProgram-data independenceStructure of data files is stored in DBMS catalog separately from access programsCopyright © 2011 Ramez Elmasri and Shamkant NavatheData abstractionAllows program-data independence and program-operation independenceConceptual representation of dataDoes not include details of how data is stored or how operations are implementedData model Type of data abstraction used to provide conceptual representationData AbstractionCopyright © 2011 Ramez Elmasri and Shamkant NavatheSupport of Multiple Views of the DataView Subset of the database Contains virtual data derived from the database files but is not explicitly storedMultiuser DBMS Users have a variety of distinct applicationsMust provide facilities for defining multiple viewsCopyright © 2011 Ramez Elmasri and Shamkant NavatheSharing of Data and Multiuser Transaction ProcessingAllow multiple users to access the database at the same timeConcurrency control software Ensure that several users trying to update the same data do so in a controlled manner •Result of the updates is correctCopyright © 2011 Ramez Elmasri and Shamkant