Education And Debate

ABC of Medical Computing: STORING AND MANAGING DATA ON A COMPUTER

BMJ 1995; 311 doi: https://doi.org/10.1136/bmj.311.7004.562 (Published 26 August 1995) Cite this as: BMJ 1995;311:562
  1. Nicholas Lee,
  2. Andrew Millman,
  3. Martin Osborne,
  4. John Cox

    All readers will be familiar with the traditional card index which is used to store relatively simple information such as a list of books in a library. Database programs are the electronic equivalent of a card index but offer several advantages. Most important of these is the ability to search and analyse the stored data rapidly and reliably. In addition to this, large amounts of information can be stored in a fraction of the space that would be required for equivalent paper records; several people on a network or multiuser system can use the same database simultaneously; and the results of searches can easily be printed in the form of a report. Furthermore, any stored data can be used by other programs such as a word processor (for creating circular letters or mailing labels), a spreadsheet (for manipulation and charting of the data), or a statistical program (for detailed analysis).

    Structure of databases

    Information stored in a database is broken down into manageable portions which are stored in separate compartments called fields and records. For example, a surname would be entered into one field, and the first name or initial and date of birth into subsequent fields. A collection of fields relating to one person or event is called a record. A database can contain an unlimited number of records.

    Flatfile databases

    Flatfile databases are the most basic type and are analogous to a card index. They are easy to create with any database program and are ideal for storing simple information such as a list of names and addresses. They offer all the facilities that many people are likely to need.

    Simple flatfile database.

    Relational databases

    In a relational database information is stored in several separate, cross referenced database files. Although more complex, this structure allows very powerful and efficient systems to be developed. A good …

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