Final answer:
SQL Server is not open source and requires a purchase for full-featured versions, although a limited free edition is available. Open source alternatives like MySQL and PostgreSQL are truly free for most uses.
Step-by-step explanation:
Microsoft SQL Server is a proprietary 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—which may run either on the same computer or on another computer across a network (including the Internet).
Microsoft markets at least a dozen different editions of Microsoft SQL Server, aimed at different audiences and for workloads ranging from small single-machine applications to large Internet-facing applications with many concurrent users. The statement that SQL Server is an open source DBMS and is free for most applications is false. SQL Server is a proprietary software developed by Microsoft.
While it offers a free edition called SQL Server Express, which has certain limitations like database size and number of cores, the full-featured versions of SQL Server require a purchase or a subscription. However, there are open source DBMS options available in the market such as MySQL, PostgreSQL, and SQLite which are truly free for most applications.