Difference between revisions of "Relational database"

Revision as of 08:22, 22 February 2016

A relational database is a digital database whose organization is based on the relational model of data, as proposed by Edgar F. Codd in 1970.

Description

This model organizes data into one or more tables (or "relations") of rows and columns, with a unique key for each row.

Generally, each entity type described in a database has its own table, the rows representing instances of that type of entity and the columns representing values attributed to that instance.

Because each row in a table has its own unique key, rows in a table can be linked to rows in other tables by storing the unique key of the row to which it should be linked (where such unique key is known as a "foreign key").

Codd showed that data relationships of arbitrary complexity can be represented using this simple set of concepts.

Relational database management systems

The various software systems used to maintain relational databases are known as relational database management systems (RDBMS).

Structured Query Language

Virtually all relational database systems use Structured Query Language (SQL) as the language for querying and maintaining the database.

See also

• Candidate key
• Codd's 12 rules
• Computer science
• Data
• Database
• Data (computing)
• Database normalization
• Database schema
• Edgar F. Codd
• Entity-relationship model
• Foreign key
• Null (SQL)
• Primary key
• Relational database management system
• Relational model
• SQL
• Unique identifier

External links

• Relational database @ Wikipedia