What is a relational database management system?

A relational database management system (RDBMS) is software that manages databases based on the relational model.

In more detail, an RDBMS is a type of database management system (DBMS) that stores data in a structured format, using rows and columns. This structure allows users to identify and access data in relation to other pieces of data in the database. The relational model means that logical data structures, known as tables or relations, are used to organise the data. Each table has a key field that uniquely identifies each row, and that key field can be used to connect one table of data to another.

The term 'relational database' was invented by E. F. Codd at IBM in 1970. Codd's model is now the most widely used database model, and all major DBMSs are based on it. These include MySQL, MS SQL Server, and Oracle Database.

RDBMSs have many advantages. They can reduce data redundancy and inconsistency, provide data integrity, support complex queries and provide security for the data. They also allow for data independence, meaning that applications do not need to be modified if the structure of the database changes.

However, RDBMSs also have some limitations. They can be complex and difficult to set up, and they may not be suitable for all types of applications. For example, they may not be the best choice for handling unstructured data, such as social media posts or images.

In an RDBMS, data can be manipulated using a relational language. The most common language is SQL (Structured Query Language), which allows users to create, update, delete and retrieve data. SQL is a standard language for managing data held in an RDBMS, or for stream processing in a relational data stream management system (RDSMS).

In conclusion, an RDBMS is a powerful tool for managing structured data. It provides a flexible and efficient way to store, retrieve and manipulate data, and it is the basis for many of the world's most widely used database systems.