Changing the SQL Server Database Owner
In SQL Server, the owner of the current database can be changed. Any user, a SQL Server login or Microsoft Windows user, who has access to connect to SQL Server can become the owner of a database.
Ownership of the system databases cannot be changed.
ALTER AUTHORIZATION can be used to change the ownership of any entity that has an owner. Ownership of database-contained entities can be transferred to any database-level principal. Ownership of server-level entities can be transferred only to server-level principals.
ALTER AUTHORIZATION ON DATABASE::[my_db] TO [sa];
Reference:
Changing the Database Owner: http://msdn.microsoft.com/en-us/library/ms190909(v=sql.105).aspx
ALTER AUTHORIZATION (Transact-SQL): http://msdn.microsoft.com/en-us/library/ms187359(v=sql.105).aspx
