Use this SQL server script from the SQL query window to rename an existing database. The script below will place the database in single user mode then rename the device and put then new device name back into multi user mode for use.

SQL Script:

Use Master

Go

Sp_DbOption <Current_Database>, 'Single User', True

Go

Exec Sp_ReNameDb '', ''

Go

Sp_DbOption <New_Database_Name>, 'Single User', False

Go

Note: You must restart or refresh the Query Analyzer to view the name change

Archived from: http://myitforum.com/cs2/blogs/dhite/archive/2007/12/30/sql-script-to-rename-an-existing-sql-server-database.aspx