Who is in MSSQL

USE Master

DECLARE @dbid INT
SELECT @dbid = dbid FROM sys.sysdatabases WHERE name = ”

IF EXISTS (SELECT spid FROM sys.sysprocesses WHERE dbid = @dbid)
BEGIN
RAISERROR (’The restore cannot be done’, 16, 1)
SELECT ‘These processes are blocking the restore from occurring’ AS Note, spid, last_batch, status, hostname, loginame FROM sys.sysprocesses WHERE dbid = @dbid
END

Source: http://blog.sqlauthority.com/2007/12/07/sql-server-fix-error-3702-cannot-drop-database-because-it-is-currently-in-use/