Dear brien,
After download this package, you can install it on your end and then have some test of it, it supports sub folders.
Installation steps:
2. unzip it
3. create database "customfileprovider"
4. execute "CustomFileProvider\SqlSample\fsitems.sql" against this database
5. Open file "SqlFileStorage.cs"
6. You can find the following line:
You can update this line, please make sure this user has full permission of database
7. If you update this line, you need build it again, and generate the CustomFileProvider.dll
8. Run UseSql.aspx in IIS or visual studio
9. Click button "Insert Image"
10. You will be able to create folders and sub folders, and then have some test
Thanks for asking