Error 924
Severity Level 14
Message Text
Database '%.*ls' is already open and can only have one user at a time.
Explanation
This error occurs when trying to access a database that is already in use by another user or session. Microsoft® SQL Server™ detected an attempt to access a database that is in single-user mode.
Action
Verify that the database in question is actually in single-user mode by executing this query (substitute your database name for <database>).
sp_helpdb <database>
GO
If the database is truly in single-user mode, the status result set column heading will list single user as the access mode.
To see what login is accessing the database, execute sp_who and scan the dbname result set column heading for the specified database.
If single-user mode privilege is a problem, contact your system administrator and ask to have the single-user mode database option set to multiuser. The system administrator can do so by executing sp_dboption from the master database, as shown here:
sp_dboption database, 'single user', false