MySQL is a full-featured open source relational database management system based on Structured Query Language. It is used for adding, removing, and modifying information in the database.A website that uses MySQL may include Web pages that access information from a database.
Microsoft SQL Server
Microsoft SQL Server is widely used in many businesses for a variety of applications. Microsoft SQL Server is the high-performance relational database management system developed by Microsoft for storing and retrieving data as requested by software applications.
PostgreSQL is an open-source, object-relational database management system. As a database server, its primary function is to store data securely, and to allow for retrieval at the request of software applications.Commonly supported objects include views, stored procedures, indexes, triggers and object-defined data types.
MariaDB has developed some interesting features and replaced mysql in many places. MariaDB has better storage dual engine and allow you to run SQL and NoSQL in a single database system which is provided by cassandra. Mariadb also supports TokuDB, which can handle big data for large organization and corporate users.