Relational Model

The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F. Codd. In the relational model of a database, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.

The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.

Most implementations of the relational model use the SQL data definition and query language. A table in an SQL database schema corresponds to a predicate variable; the contents of a table to a relation; key constraints, other constraints, and SQL queries correspond to predicates. However, SQL databases, including DB2, deviate from the relational model in many details; Codd fiercely argued against deviations that compromise the original principles.

Read more about Relational ModelOverview, History, Set-theoretic Formulation

Other articles related to "relational model, relational, model":

RDM Embedded - Standard Functionality - Data Modeling - Relational Model
... RDM allows a database to be defined using SQL, the predominant relational database language ... Relationships in a pure relational model are defined by comparing column values in one table to column values in another ...
Tuple Relational Calculus
... Codd as part of the relational model, in order to provide a declarative database-query language for this data model ... of which the latter, although far less faithful to the original relational model and calculus, is now the de-facto-standard database-query language viz ... a dialect of SQL is used by nearly every relational-database-management system ...
Database Model - Models - Relational Model
... The relational model was introduced by E.F ... It is a mathematical model defined in terms of predicate logic and set theory ... The products that are generally referred to as relational databases in fact implement a model that is only an approximation to the mathematical model defined by Codd ...
Data Maintenance - Major Database Functional Areas - Database Languages - SQL For The Relational Model
... SQL is a standard relational model language supported by all the relational DBMSs ... SQL was one of the first commercial languages for the relational model ... Despite not adhering to the relational model as described by Codd, it has become the most widely used database language ...

Famous quotes containing the word model:

    One of the most important things we adults can do for young children is to model the kind of person we would like them to be.
    Carol B. Hillman (20th century)