In the relational

database model,

data can be visualized as being stored in a number of tables, where each table represents a relation. Columns in the table are

attributes of each

relation, while the rows in the table consist of tuples that describe each

instance of the relation.

The relation schema is defined as R(A_{1}, A_{2}...A_{n}) where R is the name of the relation and each attribute A_{i} is the role a domain (for example, the set of all 9-digit integers as a domain for social security number) plays in the relation. The degree of R is the number of attributes in its schema.

An instance, or relation state of a relation, r(R) consists of a set of n-tuples r{t_{1}, t_{2}, .... , t_{n}}.

Tables in the relational database model are manipulated through relational algebra.