I used Sybase ASE on Linux in the early 2000s. It was a joy to use back then. Same dialect of SQL as Microsoft SQL Server, easy to set up and work with.
Microsoft SQL Server has since diverged to the point of being a completely different codebase, whereas Sybase stagnated and were acquired by SAP.
Sybase 11.0.3.3 for Linux was made free for production use somewhere around 2002. It is still useful for some applications, if you can find the binaries, http://froebe.net/blog/2013/03/10/howto-installing-and-runni...