Find Unused Permission Lists

This query should find unused permission lists that could be deleted.

SELECT * FROM PSCLASSDEFN A
WHERE NOT EXISTS 
    ( SELECT 'X' FROM PSUSERCLASSVW
      B WHERE A.CLASSID = B.CLASSID )
AND NOT EXISTS
    (SELECT 'X' FROM  
      PSOPRDEFN B 
      WHERE A.CLASSID = B.OPRCLASS)
AND NOT EXISTS
    (SELECT 'X' FROM 
     PSOPRDEFN B 
      WHERE A.CLASSID = B.PRCSPRFLCLS)
AND NOT EXISTS 
     (SELECT 'X' FROM 
        PSOPRDEFN B 
       WHERE A.CLASSID = B.DEFAULTNAVHP)
AND NOT 
     EXISTS (SELECT 'X' FROM 
         PSOPRDEFN B 
        WHERE A.CLASSID = B.ROWSECCLASS)
AND A.LASTUPDOPRID <> 'PPLSOFT'
ORDER BY CLASSID ;