MS SQL and MySQL are both SQL servers. That means that they both speak a flavor of Structured Query Language (SQL) and they both store data in a relational database form. That said, there are myriad differences between them, and many people use the features of each server to perform duties well above and beyond what SQL is meant to do.
So that’s a qualified “Yes” to your questions. Yes, it can be done, but it’s not necessarily a simple thing. It all depends on what the previous incarnation was doing in the database.
If all MS SQL was doing was storing a set of tabular data, similar to what you could do with Excel, then it should take minutes to dump the data in a format that can restore directly into MySQL. But if there were stored procedures and triggers in use, there might not be a direct equivalent available in MySQL without some re-engineering.
So that’s a qualified “Yes” to your questions. Yes, it can be done,
but it’s not necessarily a simple thing. It all depends on what the
previous incarnation was doing in the database.
Well, further investigation has revealed the whole might actually
just be a CMS.
If that is the case, then I will happily forget all about it, and
migrate the whole thing to WebYep. I’ve also cross-posted my question
on another forum, and got a good selection of answers, and widened my
knowledge a bit further on the “back office” stuff.
If, however, it turns out to be something deeper, then we might have
to look at a Windows server setup. (Boo!)
There are a lot of CMSs that allow you to use a variety of different databases as their storage container, without any change to the application. Depending on which CMS is in use, this may be as simple as picking the database engine out of a list.
If you do end up settling for Windows, I recommend Rackspace. Not the cheapest by a long way, but your site has less chance of being hacked, which is a huge concern on that platform without ceaseless vigilance and patching.