Relational database

A relational database is a collection of data items organized as a set of formally described tables from which data can be accessed easily. A relational database is created using the relational model. The software used in a relational database is called a relational database management system (RDBMS). A relational database is the predominant choice in storing data, over other models like the hierarchical database model or the network model. It consists of n number tables and each table has its own primary key.

Relational database theory uses a set of mathematical terms, which are roughly equivalent to SQL database terminology. The table below summarizes some of the most important relational database terms and their SQL database equivalents.