**Relational Data Model**

In the relational data model, the data is organized into a table.(i.e. row and columns). These tables are called relations. A row in a table represents a relationship between a set of values. Since a table is a collection of such relationships, it is generally referred to as using a mathematical term relation, from which the relation data model derives its name.

**Terms used in Relational model**

**Relation:**

A table storing logically related data.

**Domain:**

This a pool of values from which the actual value appearing in a given column are drawn.

**Tuple:**

A row of a relation.

**Attribute:**

A column of a relation.

**Degree:**

Number of attributes ina relation.

**Cardinality:**

Number of rows in a relation.

**View:**

It is a virtual table that does not really exist in its own right but it is instead derived from one or more base tables.

**Primary key:**

This refers to a set of one or more attributes that can uniquely identify tuples within a relation.

**Candidate key:**

All attribute combinations inside a relation that can serve as the primary key.

**Alternate key:**

A candidate key that is not the primary key is called a candidate key.

**Foreign key:**

A non-key attribute whose values are derived from the primary key of some other table.