Here is the scenario - you are in a rush to restore a down SQL database. Then you get the dreaded:
Exclusive access could not be obtained because
the database is in use.
Don't panic. You can do two things.
Option 1
If you are using the SQL Manager Tool, you select "Options" from the side panel. On there you will find a checkbox to go into single-user mode for the Restore. This will do the trick.
If this option is grayed out, cancel the restore operation, then bring it up again. Check this box first before doing anything else. It should just work.
Option 2
If you are using the command line, use this command:
USE master
GO
ALTER DATABASE DATABASE_NAME
SET SINGLE_USER
Now do your restore as normal.
Afterward
Don't forget to make sure you are in multi-user mode!
USE master
GO
ALTER DATABASE DATABASE_NAME
SET MULTI_USER
