MySQL is one of the most popular open-source relational database management system (RDBMS). The first release was in 1995. When Sun bought MySQL, Michael “Monty” Widenius, the founder of MySQL forked MySQL, launching MariaDB, and took a part of MySQL developers with him.
Microsoft SQL Server is a relational database management system developed by Microsoft. As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications.