Databases : Coding

Sometimes information is coded before it is typed into a database. For example consider a library database where books are classified as being fiction, non-fiction or reference. This information could be stored in an alphabetic field of fixed length 11 ("non-fiction" is 11 characters long). Alternatively the classifications could be coded like this :

• Fiction coded as F
• Non-fiction coded as N
• Reference coded as R

Using these codes the information can be stored in an alphabetic field of length one. Coding information reduces the amount of storage space required and speeds up the process of typing the information in. It also makes it easier to validate data as coded information must usually be in a specific format. For coding to work properly everyone needs to know what the correct codes are.

GCSE ICT Companion 04 - (C) P Meakin 2004