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Flat File Databases


Data stored on an ICT system is stored and organised in files. When the data is organised in rows and columns with data values being repeated, it is called a flat file.

A flat file looks like a spreadsheet; it is two dimensional and has no related files (or tables). Flat files are easy to create and use (for small amounts of data). Data is often repeated in a flat file and therefore they can be quite large in size.

flat-file1

In the example above, each subject that the pupil studies has to be entered as a separate record.

Redundancy
This file has a very simple row and column structure. There are no relationships between data. The main weakness of this type of file is that data has to be repeated. Look at the entry for “Amina Ahmed”. Her name is recorded twice because she studies both English and Maths.
In a relational database system, this would not happen. The surname and forename of each person would be stored only once and a related table would be created to hold the rest of the data. The two tables would then be linked. When data is repeated unnecessarily it is said to be redundant.

If another entry is made for Amina Ahmed the file would now look like this:
flat-file2

The new entry contains data which is not correct. Amina Ahmed’s forename has been recorded as “Amy”.


Data Integrity
The more often data has been recorded the higher the possibility of the data having an error or inconsistency. The user of the data must be able to rely on the correctness and accuracy of the data. The correctness, reliability and accuracy of the data is called data integrity.

Disadvantages of flat file databases: