Relational model

Relational model, Database model.

The relational model (RM) for database management is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, where 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 relational databases use the SQL data definition and query language; these systems implement what can be regarded as an engineering approximation to the relational model. 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.

Relational database
5 months ago

Relational database ... A relational database is a digital database based on the relational model of data, as proposed by E. F. Codd in 1970. A software system used to maintain...

Database model
3 weeks ago

Database model ... database model is the relational model, which uses a table-based format. Common logical data models for databases include: Hierarchical database model It is...

Object–relational database
4 months ago

Object–relational database ... just as with pure relational systems, it supports extension of the data model with custom data types and methods. An object–relational database can be said...

Graph database
1 day ago

Graph database ... limitations of relational databases. While the graph model explicitly lays out the dependencies between nodes of data, the relational model and other NoSQL...

Data model
5 months ago

Data model ... model Hierarchical model Network model Relational model Concept-oriented model Star schema A data structure diagram (DSD) is a diagram and data model...

Object–relational impedance mismatch
1 month ago

Object–relational impedance mismatch ... The object–relational impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management...

Hierarchical database model
4 months ago

Hierarchical database model ... computer system.[citation needed] The hierarchical data model lost traction as Codd's relational model became the de facto standard used by virtually all mainstream...

Relational models theory
3 months ago

Relational models theory ... Relational models theory (RMT) is a theory of interpersonal relationships, authored by anthropologist Alan Fiske and initially developed from his fieldwork...

Database
4 months ago

Database ... systems according to the database models that they support. Relational databases became dominant in the 1980s. These model data as rows and columns in a series...

Object–relational mapping
4 months ago

Object–relational mapping ... Object database Object persistence Object–relational database Object–relational impedance mismatch Relational model SQL (Structured Query Language) Java Data...

Nested set model
3 months ago
Data modeling
5 months ago
Database normalization
5 months ago
Tuple relational calculus
5 months ago
NoSQL
1 month ago
Relational calculus
4 months ago
Edgar F. Codd
5 months ago
Relational algebra
4 months ago
Entity–relationship model
5 months ago
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