database The product of the
database design process which
aims to identify and organize the required data logically and
physically.
A data model says what information is to be contained in a
database, how the information will be used, and how the items
in the database will be related to each other.
For example, a data model might specify that a customer is
represented by a customer name and credit card number and a
product as a product code and price, and that there is a
one-to-many relation between a customer and a product.
It can be difficult to change a database layout once code has
been written and data inserted. A well thought-out data model
reduces the need for such changes. Data modelling enhances
application maintainability and future systems may re-use
parts of existing models, which should lower development
costs.
A data modelling language is a mathematical formalism with a
notation for describing data structures and a set of
operations used to manipulate and validate that data.
One of the most widely used methods for developing data models
the most widely used type of data model. Another example is
["Principles of Database and Knowledge-Base Systems",
J.D. Ullman, Volume I, Computer Science Press, 1988, p. 32].
(2000-06-24)