Database Systems - Relational & Flatfile and Definitions
- Created by: lauren778
- Created on: 10-04-18 13:24
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- Database Systems
- Flat file databases
- Data is held in a single table, or in separate, unrelated tables.
- Relational Databases
- Definition
- A large collection of data items and links between them, structured in such a way that it allows it to be accessed by a number of different application programs.
- Organised to solve issues with Data Consistency, Redundancy, Integrity and Independence
- Definition
- Data Consistency
- Where the same data has exactly the same value and formatting throughout, normally because it is only stored once.
- Data Redundancy
- When data is stored more than once. If data in one file is changed, it will also have to be changed in the other file or table.
- Data Integrity
- The correctness of the data. Problems could be avoided using validation and verification.
- Data Independence
- Keeping data separate from the applications which use it.
- Eg. A booking system uses a DBMS to store bookings. Customers never see the complex DBMS - they use an internet-based front end.
- Keeping data separate from the applications which use it.
- Data Normalisation
- A staged mathematical process which removes repeated groups of data and inconsistencies.
- Flat file databases
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