We’ve integrated in-house Microsoft SQL Server databases with public PHP web sites a number of times, now. Until today, this meant dealing with Windows VPSes for even modest sites, simply because we were unable to find a Windows shared hosting plan which permitted access to remote databases, and all the research I could find suggested connecting to MS SQL from PHP on Linux was an absolute mess.
Those days appear to be over.
yum install php-mssql
That, my friends, is all we had to do, thanks to the atomic rocket turtle repository and our earlier efforts to modernize our server.