| slovo | definícia |
data model
(foldoc) | data model
data modelling
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)
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| | podobné slovo | definícia |
content data model
(foldoc) | Content Data Model
(CDM) An SGML-based
specification for interactive maintenance manuals, developed by
the Air Force Human Resourceas Laboratory (AFHRL) with assistance
from RJO Enterprises, Incorporated. CDM models data hierachically
and data are identified by their content structure with SGML
mark-up used to identify information classes such as "system
information", "functions", "tasks" and "steps".
(http://www.dtic.mil/dtic/tr/fulltext/u2/a205916.pdf).
["Final Report - Content Data Model of Organizational Maintenance
Information for Automated Interchange of Technical Source Data.",
Chicago, Illinois, Datalogics, Inc., 1998-07-07].
(2014-10-20)
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data modeling
(foldoc) | data modeling
US spelling of "data modelling".
(2000-06-24)
|
data modelling
(foldoc) | data model
data modelling
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)
|
relational data model
(foldoc) | relational data model
relational model
(Or "relational model") A data model introduced
by E.F. Codd in 1970, particularly well suited for business
data management. In this model, data are organised in
tables. The set of names of the columns is called the
"schema" of the table.
Here is an example table with the schema (account number,
amount) and 3 lines.
account number amount
-------------- ---------
12343243546456 +30000.00
23149875245824 +2345.33
18479827492874 -123.25
The data can be manipulated using a relational algebra.
SQL is a standard language for talking to a database built
on the relational model (a "relational database").
["A relational model for large shared data banks"
Communications of ACM 13:6, pp 377-387].
(1998-10-05)
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