Database Systems. What is a database? A database is an organised store of data items.

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Database Systems

Transcript of Database Systems. What is a database? A database is an organised store of data items.

Page 1: Database Systems. What is a database? A database is an organised store of data items.

Database Systems

Page 2: Database Systems. What is a database? A database is an organised store of data items.

What is a database?

A database is an organised store of data items.

Page 3: 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.

Page 4: Database Systems. What is a database? A database is an organised store of data items.

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

Page 5: Database Systems. What is a database? A database is an organised store of data items.

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.

Page 6: Database Systems. What is a database? A database is an organised store of data items.

What are the problems with a flat file database?Redundancy• Large amounts of duplicated data• Makes data entry slower• Uses disk space

Reduced data integrityMore 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

Page 7: Database Systems. What is a database? A database is an organised store of data items.

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