Metadata

Metadata , or "data about data", is used to inform operators and users of the data warehouse about its status and the information held within the data warehouse. Examples of
data warehouse metadata include the most recent data load date, the business meaning of a data item and the number of users that are logged in currently.

Natural Language

It is difficult for a system to understand natural language due to its ambiguity in sentence structure, syntax, construction and meaning. Accordingly it is not possible to design an interface given this problem. However systems can be designed to understand a subset of a language which implies the use of natural language in a restricted domain.

STRUCTURED QUERY LANGUAGE AND OTHER QUERY LANGUAGES

A query language is a set of commands to create, update and access data from a database allowing users to raise adhoc queries / questions interactively without the help of programmers. A structured query language (SQL) is a set of thirty (30) English like commands which has since become an adoptable standard. The structured query language syntax use some set of commands regardless of the database management system software like ‘Select’, ‘From’, ‘Where’. For example, after ‘Select’ a user lists the fields, after ‘From’ the names of the files/group of records containing these fields are listed, after ‘Where’ conditions for search of the records are listed.

COMPUTER OUTPUT MICROFILM

Computer output microfilm (COM) is an output technique that records output from a computer as microscopic images on roll or sheet film. The images stored on COM are the same as the images, which would be printed on paper. The COM recording process reduces characters 24, 42 or 48 times smaller than would be produced from a printer. The information is then recorded on sheet film called 16 mm, 35 mm microfilm or 105 mm microfiche. The data to be recorded on the microfilm can come directly from the computer (online) or from magnetic tape, which is produced by the computer (off-line) The data is read into a recorder where, in most systems, it is displayed internally on a CRT. As the data is displayed on the CRT, a camera takes a picture of it and places it on the film. The film is then processed, either in the recorder unit or separately. After it is processed, it can be retrieved and viewed by the user.

The Track Ball

A track ball is a pointing device that works like an upside-down mouse. The user rests his thumb on the exposed ball and his fingers on the buttons. To move the cursor around the screen, the ball is rolled with the thumb. Since the whole device is not moved, a track ball requires less space than a mouse. So when space is limited, a track ball can be a boom. Track balls are particularly popular among users of notebook computers, and are built into Apple Computer’s Power Book and IBM ThinkPad notebooks.