<
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
is the
entity-relationship model. The
relational model is
the most widely used type of
data model. Another example is
NIAM.
[
"Principles of Database and Knowledge-Base Systems",
J.D. Ullman, Volume I, Computer Science Press, 1988, p. 32].
(2000-06-24)