You can configure Orchard CMS to use a built-in SQL Server Compact database.
I want to connect to, and query, this database.
Where does Orchard create it?
Using the development installation of Orchard, the CMS creates the SQL Server CE .sdf file in the src/Orchard.Web/App_Data/sites/NameOfTheSite
directory.
You can connect to it using SQL Management Studio (up to 2012) by following these steps:
1. File -> Connect Object Explorer...
2. Change 'Server Type' to 'SQL Server Compact Edition'
3. Select < Browse for more...>
4. Browse to and select your .sdf file.
For versions of SQL Management Studio 2012 and above, a third-party tool is required.
See this question for further details.