View Definition

View Definition

In a database management system, a view is a way of portraying information in the database. This can be done by arranging the data items in a specific order, by highlighting certain items, or by showing only certain items. For any database, there are a number of possible views that may be specified. Databases with many items tend to have more possible views than databases with few items. Often thought of as a virtual table, the view doesn’t actually store information itself, but just pulls it out of one or more existing tables. Although impermanent, a view may be accessed repeatedly by storing its criteria in a query.

The best view for a particular purpose depends on the information the user needs. For example, in a telephone directory, a user might want to look up the name associated with a number, without concern for the street address. The best view for this purpose would have two columns: the phone numbers (in numeric sequence) in the first column, and the name associated with each number in the second column. Another user might want to look up the phone number associated with a street address, without any need to know the name. The best view for this purpose would have two columns: the street addresses (in alphanumeric order) in the first column, and the phone number in the second column.