How to Use a correlated subquery to get sum of colums for particular items

How to Use a correlated subquery to get sum of colums for particular items

select itemid from table1 A
where col1 = 'sp'
and amt <>
  (select sum(amt) from table1 B
   where B.itemid = A.itemid
   and col1 in ('a','b')
  )
;