A database is in principle just a large collection of related or separate data, systematically stored in a computer. It should be possible for the data to be easily entered into the database-structure and afterwards also easily read, corrected and processed. The later analysis of data from such a database is greatly enhanced by the availability of special query languages and statistical analysis programs, not only for serial items but also for large combinations of data. Query languages, such as SQL (Structured Query Language) developed especially for these purposes, make databases easily...