Kĩ thuật lập trình - Chương 8: Personal technology

1Personal Technology8.1 Managing Files: Basic Concepts8.2 Database Management Systems8.3 Database Models8.4 Data Mining8.5 Databases & The Digital Economy8.6 Using Databases to Help Make Decisions8.7 Artificial Intelligence8.8 The Ethics of Using DatabasesChapter8McGraw-Hill/Irwin© 2007 The McGraw-Hill Companies, Inc. All rights reserved.Managing Files: Basic ConceptsA database is a logically organized collection of related data designed and built for a specific purposeData is stored hierarchically for easier storage and retrievalFiles: collections of related recordsRecords: collections of related fieldsField: unit of data containing 1 or more charactersCharacter: a letter number or special character made of bitsBit: a 0 or 13Managing Files: Basic ConceptsKey Field – the field that identifies a recordOften an identifying number, such as social security numberPrimary keys must be uniqueKeys are used to pick records out of a databaseUnique keys make records stand out from each otherIf two records had the same key, then you might not pick the correct oneNonprimary keys are used to sort records in different waysForeign keys are fields that appear in two different tables and are used to relate one table to another4Managing Files: Basic Concepts This example shows a sample database in Microsoft Access. Products is a table. ProductID is the primary key of the Product table. ProductID is also a foreign key in the Orders table5Managing Files: Basic ConceptsProgram files are files containing software instructionsSource program files are written by the software developer in the programming languageDouble-clicking on them won’t run themThey have file extensions like .cpp, .jav, .basExecutable files are program files translated so they can be executed on the computerDouble-clicking on them will cause them to runThey have file extensions like .exe or .com6Managing Files: Basic ConceptsData files are files that contain data such as words, numbers, pictures, or soundsThese are the files that are used in databasesThey have extensions such as .txt .mdb, and .xlsGraphics files have extensions like .tiff, .jpeg, and .pngAudio files have extensions such as .mp3, .wav, and .midAnimation/video files have extensions such as .qt, .mpg, .avi, and .rmData files are often compressed to save space and transmit them faster Compression removes repetitive elements from a file7Database Management SystemsSoftware written specifically to control the structure of a database and access to the dataReduced data redundancyRedundant data is stored in multiple places, which causes problems keeping all the copies currentImproved data integrityMeans the data is accurate, consistent, and up to dateIncreased securityLimits who can create, read, update, and delete the dataEase of data maintenanceOffer validation checks, backup utilities, and procedures for data inserting, updating, and deletion8Database Management Systems3 Principal ComponentsData DictionaryA repository that stores the data definitions and descriptions of the structure of the data and the databaseDBMS UtilitiesPrograms that allow you to maintain the database by creating, editing, deleting data, records, and filesAlso include automated backup and recoveryReport GeneratorProgram for producing an on-screen or printed document form all or part of a database9Database Management SystemsDatabase AdministratorDatabase Administrator (DBA)A high-paid, responsible position within an organizationCoordinates all related activities and needs for an organization’s databaseEnsures the database’sRecoverabilityIntegritySecurityAvailabilityReliabilityPerformance Discussion Question: Did you know that 93% of companies that lost their data center for 10 days or more due to a disaster filed for bankruptcy within a year?10Database ModelsHierarchical databaseNetwork databaseRelational databaseObject-oriented databaseMultidimensional databaseFields or records are arranged in a family tree, with child records subordinate to parent or higher-level recordsLike a hierarchical database, but each child record can have more than one parent recordRelates, or connects, data in different files through the use of a key, or common data elementUses objects (software written in small, reusable chunks) as elements within database filesModels data as facts, dimensions, or numerical measures for use in the interactive analysis of large amounts of data11Database ModelsHierarchical DatabasesFields or records are arranged in related groups resembling a family tree with child (low-level) records subordinate to parent (high-level) recordsRoot record is the parent record at the top of the database, and data is accessed through the hierarchyOldest and simplest; used in mainframes12Database ModelsNetwork DatabaseSimilar to a hierarchical database, but each child record can have more than one parent recordUsed principally with mainframe computersRequires the database structure to be defined in advance13Database ModelsRelational DatabaseRelates or connects data in different files through the use of a key, or common data elementExamples are Oracle, Informix, SybaseData exists independently of how it is physically storedUsers don’t need to know data structure to use the databaseUses SQL (structured query language) to create, modify, maintain, and query the dataQuery by Example uses sample records or forms to allow users to define the qualifications for choosing records14Database ModelsObject-oriented DatabasesUse “objects”, software written in small, manageable chunks, as elements within data filesAn object consists of Data in any form, including audio, graphics, and videoInstructions on the action to be taken with the dataExamples include FastObjects, GemStone, Objectivity DB, Jasmine Object Database, and KE ExpressTypes includeWeb databaseHypermedia database15Database ModelsMultidimensional DatabaseModels data as facts, dimensions, or numerical answers for use in the interactive analysis of large amounts of data for decision-making purposesAllows users to ask questions in colloquial EnglishUse OLAP (Online Analytical Processing) software to provide answers to complex database queries16Data MiningIs the computer-assisted process of sifting through and analyzing vast amounts of data to extract hidden patterns and meaning and to discover new knowledgeData is fed into a Data Warehouse through the following stepsIdentify and connect to data sourcesPerform data fusion and data cleansingObtain both data and meta-data (data about the data)Transport data and meta-data to the Data WarehouseData Warehouse is a special database that shows detailed and summary data from multiple sources17Data MiningMethods for searching for patterns in the data and interpreting the resultsRegression analysisDevelops a formula to fit patterns in the data that has been extractedFormula is applied to other data sets to predict future trendsClassification analysisA statistical pattern recognition process that is applied to data sets with more than just numerical data18Data MiningApplications includeA phone company identifying customers with large bills, who were really small businesses trying to pay the cheaper residential rateA coach in the Gymnastics Federation used it to discover what long-term factors contributed to athletes’ performanceRetail stores use it to predict future purchase patterns to help them choose which products to stock for the future19Databases & The Digital EconomyE-CommerceThe buying and selling of products and services through computer networksExamples of some e-tailers (electronic retailers): www.amazon.com sells books and music onlinewww.sees.com sells candy onlinewww.ebay.com connects buyers with sellers online using online auctions20Databases & The Digital EconomyInnovative e-tailer technologies make online shopping easierOne-click optionAllows you to click on an item and immediately go to the check-out process360-degree imagesAllow you to see all sides of an itemOrder trackingBar codes are assigned to items being shipped that allow customers to check shipping progress via the internetShop botsAre programs that help users search for a particular product of service21Databases & The Digital EconomyTypes of E-CommerceBusiness-to-business (B2B)A business sells to other businesses using the internet or a private network to cut transaction costs and increase efficienciesBusiness-to-consumer (B2C)A business sells goods or services to consumersConsumer-to-consumer (C2C)Consumers sell goods or services directly to other consumers with the help of a third party, such as eBay.22Using Databases to Help Make DecisionsWhat are the qualities of good information?Correct and verifiableComplete yet conciseCost effectiveCurrentAccessible23Using Databases to Help Make DecisionsMost organizations have 6 departments to which information must flowResearch and developmentProduction (or operations)Marketing and salesAccounting and financeHuman resources (personnel)Information systems (IS)Information flows horizontally between departments24Using Databases to Help Make DecisionsBesides the 6 departments, many organizations also have 3 levels of managementStrategic-level managementTop managers concerned with strategic or long-term planning and decisionsTactical-level managementMiddle level managers who make decisions to implement the strategic goals set for the organizationOperational-level managementLow-level supervisors make daily operational decisionsInformation flows vertically between management levels25Using Databases to Help Make DecisionsDecentralized Organizations – a new structureEmployees increasingly telecommute – some staff have no desk or office at workEmployees communicate with each other more via email than in personCompanies use Groupware CSCW (computer-supported cooperative work) systems to enable cooperative work by groups of peopleThe management structure is flattened as employees are given more authority to make day-to-day decisions26Using Databases to Help Make Decisions6 computer-based information systemsOffice information systemsTransaction processing systemsManagement information systemsDecision support systemsExecutive support systemsExpert systems27Using Databases to Help Make DecisionsTransaction Processing System (TPS)Transactions are recorded events of routine business activities such as bills, orders, and inventoryTPS systems keep track of the transactions needed to conduct a businessTPS systems are used by operational managers to track business activitiesTransactions database provides the basis for management information systems and decision support systemsHas anyone seen the movie “Office Space”? In that movie, the hero’s boss is nagging him about formatting the TPS report correctly. Now you know what TPS means!28Using Databases to Help Make DecisionsManagement Information Systems (MIS)Computer-based information system that uses data recorded by a TPS as input to programs that produce routine reports as outputFeaturesInputs are processed transaction data. Outputs are summarized structured reportsDesigned for tactical managersDraws from all departmentsProduces several kinds or reports: summary, exception, periodic, and demand29Using Databases to Help Make DecisionsDecision Support Systems (DSS)Computer information system that provides a flexible tool for analysis and helps management focus on the futureFeaturesInputs are external data and internal data such as summarized reports and processed transaction data. Outputs are demand reportsMainly for tactical managersProduces analytic modelsDeveloped to support the types of decisions faced by managers in specific industries30Using Databases to Help Make DecisionsExecutive Support SystemsAn easy-to-use DSS made especially for strategic managers to support strategic decision-makingMight allow executives to call up predefined reportsIncludes capability to browse through summarized information on all aspects of the organization and drill down for detailed dataAllows executives to perform “what-if” scenarios31Artificial IntelligenceExpert SystemOne of the most useful applications of Artificial Intelligence (AI)AI is a group of related technologies used to develop software and machines that emulate human qualities such as learning, reasoning, communicating, seeing, and hearingAreas includeExpert systemsNatural language processingIntelligent agentsVirtual reality and simulation devicesPattern recognitionFuzzy logicRobotics32Artificial IntelligenceThree components of an expert systemKnowledge baseAn expert system’s database of knowledge about a particular subjectInference engineThe software that controls the search of the expert system’s knowledge base and produces conclusions User interfaceThe display screen the user used to interact with the expert system33Artificial IntelligenceNatural language processingAllows users to interact with a system using normal EnglishThe study of ways for computers to recognize and understand human languageIntelligent agentsA form of software with built-in intelligence that monitors work patterns, asks questions, and performs work tasks on your behalfPattern recognitionInvolves a camera and software that identify recurring patterns in its vision and maps the pattern against patterns stored in a database34Artificial IntelligenceFuzzy logicA method of dealing with imprecise data and uncertainty, with problems that have many answers rather than oneHas been applied in running elevators to determine optimum times for elevators to waitVirtual realityA computer-generated artificial reality that projects a person into a sensation of 3-D spaceOften used with simulators to represent the behavior of physical or abstract systems35Artificial IntelligenceRoboticsThe development and study of machines that can perform work that is normally done by peopleCommonly found in manufacturing plants and also in situations where people would be in dangerNuclear plantsAssembly lines, especially paint linesChecking for land minesFighting oil-well fires36Artificial IntelligenceWeak vs. Strong A.I.Weak A.I. claims computers can be programmed to simulate human cognitionStrong A.I. claims that computers can think on a level that is equal to or better than humans, and can also achieve consciousnessCyc approach to strong A.I.A database in Austin, TX that holds 1.4 million basic truthsPlan is that Cyc will automatically make human-like assumptionsHope is that Cyc will learn on its ownCog approach to strong A.I.MIT project that is a humanoid robotTries to identify and search for patterns instead of following rules and facts37Artificial IntelligenceTest for Human IntelligenceIn 1950, Allen Turing predicted computers would be able to mimic human thinkingThe Turing test determines whether the machine is humanJudge is in another location and doesn’t see the computerIf the computer can fool the judge, it is said to be intelligentEthics in A.I.Prof. William Wallace from R.P.I. says that computer software is subtly shaped by the ethical judgments of its creatorsFor example, H.M.O. software used by health insurers steers doctors to cheaper procedures – but are they better?38The Ethics of Using DatabasesIdentity Theft concernsA crime in which thieves hijack your identity and use your good credit rating to get cash, take out loans, order credit cards, and buy things in your namePrivacy concernsName migration: getting endless junk mail and telemarketing callsRésumé rustling and online snoopingGovernment prying and spyingDiscussion Question: Has any one had their identity stolen? How long did it take you to get it straightened out?39