The relational model, first proposed in 1970 by Edgar F. Codd, departed from this tradition by insisting that applications should search for data by content, rather than by following links.

Because the relational model emphasizes search rather than navigation, it does not make relationships between different entities explicit in the form of pointers, but represents them rather using primary keys and foreign keys.

The rigidity of the relational model, in which all data is held in tables with a fixed structure of rows and columns, has increasingly been seen as a limitation when handling information that is richer or more varied in structure than the traditional ' ledger-book ' data of corporate information systems: for example, document databases, engineering databases, multimedia databases, or databases used in the molecular sciences.

The relational model is a simple model that provides flexibility.

The most common language associated with the relational model is the Structured Query Language ( SQL ), though it differs in some places.

Products offering a more general data model than the relational model are sometimes classified as post-relational.

Some of these extensions to the relational model integrate concepts from technologies that pre-date the relational model.

A major Relational model language supported by all the relational DBMSs and a standard.

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.

Clearly separating the three levels was a major feature of the relational database model implementations that dominate 21st century databases.

In practice usually a given DBMS uses the same data model for both the external and the conceptual levels ( e. g., relational model ).

DBMSs can be categorized according to the database model ( s ) that they support, such as relational or XML, the type ( s ) of computer they support, such as a server cluster or a mobile phone, the query language ( s ) that access the database, such as SQL or XQuery, performance trade-offs, such as maximum scale or maximum speed or others.

DBMSs may use a variety of database models, such as the relational model or object model, to conveniently describe and support applications.

The relational model solved this by splitting the data into a series of normalized tables ( or relations ), with optional elements being moved out of the main table to where they would take up room only if needed.

In the relational model, related records are linked together with a " key "

In the relational model, some bit of information was used as a " key ", uniquely defining a particular record.

IBM itself did one test implementation of the relational model, PRTV, and a production one, Business System 12, both now discontinued.

The normalized structure divides data into entities, which creates several tables in a relational database.

By the early 1990s, however, relational systems were dominant for all large-scale data processing applications, and they remain dominant today ( 2012 ) except in niche areas.

The vendors of relational databases have fought off competition from these newer models by extending the capabilities of their own products to support a wider variety of data types.

In the relational approach, the data would be normalized into a user table, an address table and a phone number table ( for instance ).

A relational normalised database imposes a heavy access load over physical storage of data even if it is well tuned for high performance.

Access to data can be faster because joins are often not needed ( as in a tabular implementation of a relational database ).

* Secondary storage management: Unlike relational databases, the lower-level management considerations of the data are separated from the logical data definition for clarity in design, ease of programming in the accessing application, and separation of concerns in administration.

Because of the popularity of XML, XQuery engines compete with object databases as a vehicle for storage of data that is too complex or variable to hold conveniently in a relational database.

An object database stores complex data and relationships between data directly, without mapping to relational rows and columns, and this makes them suitable for applications dealing with very complex data.

A relational database is a collection of data items organized as a set of formally described tables from which data can be accessed easily.

A relational database is the predominant choice in storing data, over other models like the hierarchical database model or the network model.

In the relational model of a database, all data is represented in terms of tuples, grouped into relations.

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.

Berkeley DB is not a relational database.

Berkeley DB has an architecture notably simpler than that of other database systems like relational database management systems.

* Carbonado – An open source relational database access layer.

A normal relational database however, is not efficient for business intelligence reports where dimensional modelling is prevalent.

:: Most modern relational databases include active database features in the form of database trigger.

In the design of a relational database, the process of organizing database relations to minimize redundancy is called normalization.

In a relational database clustering the two respective relations " Items " and " Orders " results in saving the expensive execution of a Join operation between the two relations whenever such a join is needed in a query ( the join result is already ready in storage by the clustering, available to be utilized ).

DBMSs can be categorized according to the database model ( s ) that they support, such as relational or XML, the type ( s ) of computer they support, such as a server cluster or a mobile phone, the query language ( s ) that access the database, such as SQL or XQuery, performance trade-offs, such as maximum scale or maximum speed or others.

Alternatively, and especially in connection with the relational model of database management, the relation between attributes drawn from a specified set of domains can be seen as being primary.

In some cases, denormalisation helps cover up the inefficiencies inherent in relational database software.

Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy and dependency.

Informally, a relational database table is often described as " normalized " if it is in the Third Normal Form.

They also produced one notable business application, a relational database called Cornerstone.

A key field is a field or set of fields ( a key is then said to be a composite key ) of a database ( typically a relational database ) table which together form a unique identifier for a database record ( a table entry ).