databases

databases

1. definition of data words numbers images sound etc.

2. Data validation and verification

   • types of validation
     • Spell check Range check
     • Presence check Lookup table
     • Length check Format check
     • Check digit
   • For example, a secondary school student is likely to be aged between 11 and 16. The computer can be programmed only to accept numbers between 11 and 16. This is a range check.
   • Double entry - entering the data twice and comparing the two copies. This effectively doubles the workload, and as most people are paid by the hour, it costs more too.
   • Proofreading data - this method involves someone checking the data entered against the original document. This is also time-consuming and costly.

3. Data files are stored in a number of formats, the formats depend on which application created the file to begin with. For example, Microsoft Word stores files as *.doc but Adobe Photoshop stores files in a different format - *.psd. The file extension identifies the file's format.

4. When data is transferred from one computer to another, the computer receiving the data file may not be able to read the format without the right application installed. For example, an image created in Adobe Photoshop and saved as a *.psd file (Photoshop's format) would not be readable by Microsoft Paint

5. Data can be stored temporarily in a computer's RAM as a means of transfer from one application to another. In Microsoft operating systems this feature is called the clipboard and it can copy data from one application and paste it into another. Nearly all other operating systems support this functionality.