RELATIONAL ALGEBRA Meaning and
Definition
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Relational algebra is a fundamental concept in database theory and it serves as a formal mathematical foundation for relational databases. It provides a set of operators that manipulate relations, which are tables or sets of records with a predefined schema.
The operators of relational algebra are designed to allow users to perform operations on relations to achieve a desired result. These operations can involve the selection of specific records based on certain conditions, the projection of specific attributes or fields from a relation, the union or intersection of relations, and the join of two or more relations based on a common attribute.
Relational algebra consists of six main operators: selection, projection, union, set difference, Cartesian product, and join. The selection operator is used to retrieve records satisfying a specified condition, while the projection operator is used to retrieve specific attributes from a relation. The union operator combines two relations to form a new relation that includes all the records from both relations, while the set difference operator removes records from one relation that also exist in another relation. The Cartesian product operator combines every record from one relation with every record from another relation to create a new relation, and the join operator combines records from two or more relations based on a common attribute.
Relational algebra provides a mathematical foundation for database query languages such as SQL, allowing users to express their queries and operations in a precise and systematic manner. It forms the basis for many database management systems and plays a crucial role in the design, implementation, and optimization of relational databases.
Common Misspellings for RELATIONAL ALGEBRA
- eelational algebra
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Etymology of RELATIONAL ALGEBRA
The word "relational algebra" comes from the combination of two terms: "relational" and "algebra".
1. "Relational" refers to the concept of relational databases, which were introduced by Edgar F. Codd in his 1970 paper "A Relational Model of Data for Large Shared Data Banks". In this model, data is organized into tables (relations) consisting of rows (tuples) and columns (attributes), and relationships between these tables can be established using keys.
2. "Algebra" refers to a branch of mathematics that deals with mathematical symbols and the rules for manipulating them. In the case of relational algebra, it is a formal language that defines a set of operations to manipulate and combine relations in a relational database.
Therefore, the term "relational algebra" describes the use of algebraic operations to manage and manipulate relational databases based on the relational model proposed by Codd.
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