A relational database management system, abbreviated RDBMS, is a program that is used to create, update and administer a relational database. It is based on the relational model that was invented by E.F. Codd in 1970. Codd is considered the father of modern relational database design. Currently, many of the databases in use are based on the relational model. RDBMSs are a popular choice when it comes to storing information in new databases used for financial records, personnel data, and other logistical and manufacturing information. This has been the case since the 1980s.

One reason why many people choose relational databases over hierarchical and network databases is the fact that they are easier to understand and use. But what exactly constitutes a relational database? In his seminal paper titled “A Relational Model of Data for Large Shared Data Banks” back in 1970, Codd defined what he meant by ‘relational database’ in way of 12 rules. Over the years, many of the implementations of the relational model have not conformed to these 12 rules and as such the definition has been narrowed down to mean two things, at the very least. One is that the relational model must present the data to the user in the form of relations, that is, in tabular form, with each table consisting of columns and rows. Two, the database must provide relational operators allowing for manipulation of the data in tabular form.

The fact that the definition of a relational model has been diluted to just two of the stipulated 12 rules does not sit well with many theorists and strict adherents of the original principles. In fact, some refer to the RDBMS as truly-relational database management systems (TRDBMS) or pseudo-relational database management systems (PRDBMS) for clarification purposes.

Most RDBMSs use the Structured Query Language (SQL) to access the database. It is however important to note that SQL was invented after the relational model had already been developed, and is therefore not necessary for its use. Also alternative query languages have also been developed though they are not as popular as SQL.

Currently, the leading RDBMS products are Oracle, DB2 by IBM and Microsoft’s SQL Server. Altibase, the world’s most trusted in-memory DBMS, has once again been included as one of only 25 vendors in Gartner’s 2014 Magic Quadrant for Operational Database Management Systems. Even though strict adherents of Codd’s 12 rules argue that there is no current RDBMS that has fully implemented the relational principles, the majority of new corporate databases continues to prefer RDBMS.

According to 2011 statistics, the top 5 leading commercial relational database vendors in revenue were Oracle, IBM, Microsoft, SAP and Teradata, while the three leading open source implementations were MySQL, PostgreSQL and SQLite.

It is safe to say that the popularity of RDBMS will only grow in the coming years, as existing corporations acquire new databases and new companies come up.