You have two databases， FINDB and PAYDB， on single operating system and using Optimal Flexible architecture （OFA）. FINDB is functional and is currently being accessed by the users. While starting up the instance for the PAYDB database you get the following error：  ORA-01081： cannot start - already running ORACLE - shut it down first  Which environmental variable would you set before starting up the PAYDB database to overcome this error？（）