Database & Record StructureDefinitionDatabase ComponentsDatabase FieldsSlide 5Database Records and FilesHypertext DatabaseData StructureTreesTablesDialog DatabaseDialog Database StructureLinear FileInverted FileCreation of Inverted FileSlide 16Linear File: ExampleSlide 18Slide 19IndexingRecord StructureInternet ProtocolsE-mail ProtocolsIntroduction to DialogDatabase & Record StructureDania BilalIS 530Fall 2005DefinitionA database is a collection of information organized in a way that a computer program can quickly retrieve desired pieces of data.Database ComponentsFieldsRecordsFilesDatabase FieldsPieces of information a user can accessAuthorTitleJournal nameAbstractDescriptorsOtherDatabase FieldsFields may have attributes associated with them:Numeric (e.g., accession number)Textual (e.g., author name)Database Records and FilesRecordA collection of fields which constitutes a complete set of informationFileA collection of recordsHypertext DatabaseHypertext was invented by Ted Nelson in the 1960s.In a hypertext database, objects (text, pictures, music, and other media) are linked to each other.Data StructureA scheme for organizing related pieces of information. Basic types of data structuresFiles, records, trees, tablesTreesData is organized in a hierarchical structureEach element is attached to one or more elements that is directly beneath it.Connections between elements ->branchesElements at bottom of a tree with no elements below them -> leavesTablesData is organized in rows and columnsExample: Excel spreadsheetRelational database management systems store data in the form of related tablesAleph system is based on a relational database management system (Oracle)Dialog DatabaseDocuments or surrogates are stored in a linear fileLinear file is transformed into an inverted fileDialog Database StructureLinear fileComposed of document surrogates stored in the IR system in their full, native form.Inverted fileComposed of all words included in document surrogates excluding stop words.Linear FileDocuments have to be searched in their entirety to locate specific information needed.Slow and inefficientInverted FileWords in all documents can be searched instead of the whole text of the documents themselvesFaster and more efficientCreation of Inverted FileA list of words in document surrogates is made.Each word is numbered, including phrases and excluding stop words.Words that are numbered are alphabetized (numbers precede letters)Creation of Inverted FileAlphabetized entries are followed by the document number, field (e.g., AB, DE), and the number of the entry in that field (e.g., entry in abstract as first word)Linear File: Example101The origins of Don Giovanni.Discusses the history and sources Mozart used in his opera Don Giovanni.DE: Mozart, Opera, Historical Analysis.Inverted FileOrigins 101 Ti 2Don 101 Ti 4Giovanni 101 Ti 5Discusses 101 Ab 1History 101 Ab 3Sources 101 Ab 5Mozart 101 Ab 6Used 101 Ab 7…Inverted FileMozart 101 DE 1Opera 101 DE 2Historical 101 DE 3Analysis 101 DE 4Historical Analysis 101 DE 3,4IndexingWords (keywords)Every important word in document is indexedInformation systems, for example, is indexed as 2 separate words and as a phraseInformationSystemsInformation systemsRecord StructureDialog record structure shows every field followed by the information for that field. Fields and structure varies among databasesDemo of a Dialog Record structureInternet ProtocolsHttpTelnetFile Transfer Protocol (FTP)Secure FTP (SSH)Web-based FTP (Volspace)E-mail ProtocolsSMTP (Simple Mail Transfer Protocol) Used to send e-mail between servers and between a server and client’s machine over the InternetEmail is retrieved by using a POP, IMAP, or text-based email clientPOP (Post Office Protocol)IMAP (Internet Message Access Protocol)Introduction to DialogBegin or BSelect or SSelect Steps or SSDisplay Sets or DSLogoff