Today Orchard can be used with two different databases, i.e. Sql Ce and Sql Server (including Sql Express), which provides enough options not only for simple websites but also enterprise level ones requiring better reliability and performance. In the upcoming release Orchard will also support MySql.
Downloading Orchard with MySql support
Rickard Pettersson took the time to implement it based on the current development branch which uses NHibernate 3. So you will need to clone the repositories at the latest changeset from the 1.x branch, or you can also get a zip file containing the latest verion by clicking on this link.
Setting up Orchard with MySql
Once you have downloaded the latest source code, run it and the Setup screen should now look like this.
If you have an already running MySql server, just create a database and set the connection string. The Database Table Prefix is usefull if you want to reuse the same database accross different Orchard installations.
If you don't have a running MySql server and don't want the burden of setting one up then an very easy solution is to use Windows Azure Web Sites as you can setup a free hosted MySql instance.
Click Finish Setup, play with it, and report any bug you could find.
MySql is licensed under GPL, which includes both the database server and the client libraries. Fortunately it comes with open source exceptions which let us redistribute the client libraries as explained in the FAQ below.
Q3: Can an open source software project combine and distribute any of Oracle’s GPL-licensed MySQL software with other open source software under the FOSS License Exception? Does this include the MySQL database server?
A: Open source software projects and other developers are free to use and distribute GPL-licensed MySQL software with other open source software as long as they comply with the terms of the GPL. Open source software projects and other developers can also use and distribute open source applications with the GPL-licensed MySQL Client Libraries under the terms of the FOSS License Exception without causing the entire derivative work to be subject to the GPL.
The FOSS License Exception only applies to software licensed under the FOSS licenses listed in the section above titled “FOSS License List”, and only with respect to use and distribution of Oracle’s MySQL Client Libraries.
The FOSS License Exception does not apply to the MySQL database server or other Oracle or MySQL software. The terms of the GPL apply with respect to use and distribution of the MySQL database server with any other software.
This doesn't give you the right to use MySql for free, you still need to comply with the license, but it allows Orchard to be distributed with the client libraries, as Orchard is distributed under the BSD license.