What is a relational database?

A relational database consists of a collection of tables that store particular sets of data. The invention of this database system has standardized the way that data is stored and processed. The concept of a relational database derives from the principles of relational algebra, realized as a whole by the father of relational databases, E. F. Codd. Most of the database systems in use today are based on the relational system.

The history of the relational database began with Codd’s 1970 paper, A Relational Model of Data for Large Shared Data Banks. This theory established that data should be independent of any hardware or storage system and provided for automatic navigation between the data elements. In practice, this meant that data should be stored in tables and that relationships would exist between the different data sets, or tables.

The relation is the primary unit of storage in a relational database, which is a two-dimensional table. A relational database can contain one or more of these tables. Each table consists of a unique set of rows and columns. A single record is stored in a table as a row, also known as a tuple. Attributes of the data are defined in columns, or fields, in the table. The characteristics of the data, or the column, relates one record to another. Each column has a unique name and the content within it must be of the same type.