The cost of a dnn hosting starts at around $5 a month which includes mssql, with fully managed hosting on a high end system starting at around $20 a month - increasing all the way up to cloud and dedicated webfarms.  These days you will find that professional managed web hostings these days are pretty much price compatible across platforms - and any hosting optimized for DNN will include ms sql automatically. 

As for why DNN - an ASP.NET flagship community platform would be optimized for MS SQL - I think that really explains itself.  

However, firstly - mysql is not natively supported by asp.net  - a separate mysql connector is required to be installed at the server level for such support. - this would complicate support by dnn developers.

Secondly, due to the complex nature of DNN and the myriad of modules developed for the platform - supporting more than one optimized database provider is an almost impossible task.  While the dnn database provider model does allow for use of different sql engines - it has become apparent over time that doing so is simply not practical in the real world.

One of the key reasons for this is the complex differences between the different SQL scripting extensions each server provides.  And the fact that in many cases these extensions to the SQL language are an integral part of the features that allow enhancements and optimization.  For example. in the current install there are hundreds of store procedure and install scripts written in T-SQL the mssql version of SQL.

Now having said all this - the fact that DNN does have a database provider model does mean that if someone really did have the desire to do so - they COULD modify ALL the T-SQL scripts and create a MYSQL database provider - which would in theory work.

But the simple fact is that there is not a great lot of will to do this - msql express is a free sql server - which dnn is fully optimized for already.

Westa

Thank you for all the comments, as I have said DNN is a non starter, if it cannot support MYSQL, why DNN decided to go down the path of using MS SQL, is a question only they can answer, as some of the big boys like, Google, You Tube and Yahoo all use MYSQL, As for extensions all those I have looked at, declare are free but when you get down to the nitty gritty you have to pay for it. 

Whatever happened to a real community... I must be getting old....

Once again thank you for your comments and please remeber Microsoft are not gods, I know I have worked there