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