Relational algebra

reduction of data redundancy

family of algebras used for modelling the data stored in relational databases, and defining queries on it

In database design, object-oriented programming and design, has-a (has_a or has a) is a composition relationship where one object (often called the constituted object, or part/constituent/member object) "belongs to" (is part or member of) another object (called the composite type), and behaves according to the rules of ownership. In simple words, has-a relationship in an object is called a member field of an object. Multiple has-a relationships will combine to form a possessive hierarchy.

concept in relational algebra

decomposition of a database relation such that a natural join of the resulting relations yields back the original relation