A SQL Server vs. An SQL Server

Since we reference an external solution, we must write the full name, Microsoft SQL Server, whenever possible (the same we do for every other external solution).

When talking about an instance or a database of the server, use the article a (not an) — a Microsoft SQL Server instance or a SQL Server database (since "SQL" is pronounced as [ ˈsiːkwəl ] not [ ˈɛs kjuː ˈɛl ] according to Microsoft).