Will Darby
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Mapa Mental sobre Computing Topic 5 Databases, criado por Will Darby em 11-02-2016.

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Will Darby
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Computing Topic 5 DatabasesA database is a persistentorganised store of data on acomputer systemThe importance of databasesaccurateup to dateorganisedprotected fromthose who shouldnot have accessavailable to those whoneed to use themdatabase administratorsneed to protect their dataagainst:errorslossunauthorised accessinconsistenciesinsufficient dataerrors in databases can result in:financial losslife or death situations such as incorrectnavigational data for aircraftData security and integritysecuritydata can be lost because of:an accidentflood or fireby an intrudercan be protected by:making regular backupsrestricting datahaving a mirror databasekeep audit trailsintegritymeans the data reflects realitycan be maximised by:suitable validationsoftware preventinginconsistent statesValidation and verificationvalidation - process of checkingdata when it is inputverification - checking that the datainputted is correctoperations on databasescan be listed under CRUDcreatereadupdatedeletedata matching and miningmatching comparesdifferent databases tolook for relationshipsmining looks in unrelateddatabases for relationshipsthat were misseddata modelsa model is a data structure thatattempts to represent realityflat file database -rows and columnsrows are called recordscolumns are called fieldsdata redundancy isrepetition of datahierarchical databaseuseful making an inventoryrelational databasemost usefulmost commonseparate, linked tableseach table contains info on one entityinfo only stored onceDBMSdatabase management systemsoftware that looks after databasesallows administrators to:create database applicationsprotect datakeep data consistent and accuratetransactionswhen a change takesplace in a databasemulti-user databasesif two users try to modifydata, one will failrecord locking - data can onlybe viewed until other usershave finished modifying ittools provided by DBMSstablesstructures where data is storedlinking tablesavoids data redundancydata types (text, number)forms (UI)reportssummarise dataqueriesmoduleClique duas vezes aqui para editar o textoClique e arraste este botão para criar um novo tópico