Relational model

The relational model is a data model that stores data in a simple data structure called a relation.

Relation

Essentially a table. It stores entries (rows) of related attributes (columns).

For example, let's say we want to store a student's data. This student is considered one entry in the student database. In this entry is the student's full name, home address, and GPA, which are attributes that relate to each other because they are from the same student.

Primary key

In each relation, an attribute is used as the primary key. This is the unique identifier of each entry.

Operations

The relational model specifies the following operations to be performed on the database.

Select

The select operator selects a subset of entries from a relation with a criteria.

In conjunction with the primary key, it allows the user to select a particular entry inside the database.