What

You have a database that you have been restoring transaction logs to, perhaps as part of a log shipping setup, and you now want to bring it online.

How

If your database is in recovery mode, run a command similar to the following to bring it online (replace AdventureWorks with the name of your database):

RESTORE DATABASE AdventureWorks WITH RECOVERY

If your database is in read-only mode, you will need to first disconnect all connections to that database before you can bring it online.  You can kill the active connections one by one, or just run a command similar to the following (replace AdventureWorks with the name of your database):

USE master ALTER DATABASE AdventureWorks SET OFFLINE WITH ROLLBACK IMMEDIATE ALTER DATABASE AdventureWorks SET ONLINE RESTORE DATABASE AdventureWorks WITH RECOVERY