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database, relational

Relational databases can be traced back to a database model according to E. F. Codd, an employee of the IBM Research Institute in San Jose, California. In 1970, Codd described "A Relational Model for Large Shared Data Banks" and defined the basic principles for database management.

According to Codd's principles, a relational database model based exclusively on tables consists of three components: A structural component comprising relations, a manipulable component consisting of operations for creating entire tables, and a rule set for maintaining the integrity of the database. Here, a relation is a mathematical relationship between two directly related records.

Relational databases consist of any number of individual tables that can be linked together in any way. The information is stored in columns and rows, with the rows containing the records and the columns containing the attributes, such as name, location, street, etc. To avoid ambiguities, the columns as well as the rows may only occur once and all data stored in the columns must always be of the same data type.

Example of a relational table

Example of a relational table

The storage itself can be a column-oriented or row-oriented database. In the first case one speaks of a Column-oriented Database or Columnar Database, in the second case of a Row-oriented Database.

Since relational databases fulfill certain requirements with regard to the relation of the data and their data extraction, they are particularly powerful. Therefore, a single database can be viewed in a variety of ways. It is also important that a relational database can be extended over several tables. This allows the attributes of several databases to be combined, for example, when a column contains identical attributes, such as the name or the ident number. The relational database can make selections in the columns using ordering criteria.

There are several query languages for relational databases. Structured Query Language( SQL) is a widely used and mostly standardized query language.

Englisch: database, relational
Updated at: 19.09.2019
#Words: 314
Links: database model, indium (In), database management, integrity, relation
Translations: DE

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