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Published byBrandon Deem Modified over 9 years ago
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ForenameSurnameFormSubjectTeacherGrade HarrySmithAICTMiss BunceA FionaJonesBHistoryMr EvansB HarrySmithAHistoryMr EvansB JennyFieldsBArtMiss GoldA HarrySmithAArtMiss ColdA JennyFieldsAICTMiss BunceA What is the problem with this flat file database?
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ForenameSurnameFormSubjectTeacherGrade HarrySmithAICTMiss BunceA FionaJonesBHistoryMr EvansB HarrySmithAHistoryMr EvansB JennyFieldsBArtMiss GoldA HarrySmithAArtMiss ColdA JennyFieldsAICTMiss BunceA 1.Data is duplicated – each exam entry requires the pupil data to be entered again 2.Data is inconsistent – mistakes are made 3.Difficult to add an extra field
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Large collection of data items stored in separate tables with links between them e.g. – driving school has students, lessons and lesson types – all linked by the lesson table
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You can view all the related data together
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Data independence – data and programs stored separately. You can add an extra table and it won’t affect the programs. Data consistency – data is only stored once – no danger of it being updated in one place and not in another No data redundancy – data is not duplicated unnecessarily
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More information available to users - all information is stored centrally – not in separate departments Ease of use – queries etc. Data integrity – validation ensures data is as correct as possible Greater security – authorised users – different access levels
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Complex and costly to set up Needs greater knowledge to set up Users require more training If data used for a range of applications – security and confidentiality issues arise
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Database is made of records – each record has a structure containing fields.
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Data typeDescriptionExample IntegerWhole number4 or 5 or 818809 CurrencyNumber representing a financial amount £4.55 or $0.99 StringText or charactersJosh or 41 Bridge Street Date/timeDates or times in any format 15 th May 2010 or 14:56 or 09/12/2009 BooleanData which can only be one of two states Yes or no True or false
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Query – a method of searching a database for specific information Report – printed output from a database for a specific purpose Form – an interface to a table or group of linked tables for data entry Import – data from an external data source brought into the database Export – data from the database used for another purpose – e.g. Mail merge letter
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Fields can be coded – e.g. M or F Database can have validation Each record has a key field which is a unique identifier
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