Database Systems What is a database A database
Database Systems
What is a database? A database is an organised store of data items.
What are the key terms associated with databases? Query – is when you interrogate (search ) a database to find some information e. g. Search for all females in Year 8 because they need to be sent HPV injection letters. Report – the output from a database in which the results are presented in a way controlled by the user. It is usually a formatted printout. E. g. Formatted list of pupils who study each subject to work out rooms for exams. Import/Export – the ability of software to read and use the data produced by a different piece of software e. g. Exporting names and grades into a word processing program to produce reports.
What are the key terms associated with databases? Consistency –data should be stored in a consistent format Redundancy – data which is stored more than once unnecessarily is called redundant data Independence – the data is stored separately from the applications that use it
What is a flat file database? A flat file database contains only one table of data. These could be set up in either database software or spreadsheet software. • What is a relational database? A relational database is a large collection of data items(tables) with relational links between them.
What are the problems with a flat file database? Redundancy • Large amounts of duplicated data • Makes data entry slower • Uses disk space Reduced data integrity More likely to be inaccurate! Due to: • Data input errors • Inconsistent data entry Difficult to update • If entries change all instances have to be updated Security • All users have access to the same set of data
Database security Hierarchy of passwords – this limits users to various parts of the program. E. g. A receptionist would only have access to basic patient details but a Doctor would be able to see all the information. Access rights – only certain users can access and change data. E. g. Nurse would see information on a patient but be unable to alter drug doses etc. Independence – the data is stored separately from the applications that use it
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