Relational database

Relations can be represented as two-dimensional data tables with rows and columns
The rows of a relation are called tuples.
The columns of a relation are called attributes.
The attributes draw values from a domain (a legal pool of values).
The number of tuples in a relation is called its cardinality while the number of attributes in a relation is called its degree
A relation also consists of a schema and an instance
Schema defines the structure of a relation which consists of a fixed set of attributedomain pairs.

An instance of a relation is a time-varying set of tuples where each tuple consists of attribute-value pairs.

0 comments