DB 종류 명시하면 좋을꺼 같아요.
아래는 오라클 기준인데,  다른 DB이면  "FROM DUAL" 부분만 빼면 확인될꺼예요. 

WITH dataTble (NO, TAG, VALUE) AS (
    SELECT 1, 'A', 250 FROM DUAL UNION ALL
    SELECT 1, 'A', 250 FROM DUAL UNION ALL
    SELECT 1, 'B', 500 FROM DUAL UNION ALL
    SELECT 2, 'A', 200 FROM DUAL UNION ALL
    SELECT 2, 'A', 200 FROM DUAL UNION ALL
    SELECT 2, 'B', 500 FROM DUAL 
) 
SELECT 
    DISTINCT NO 
FROM (
    SELECT 
        NO, TAG, SUM(VALUE) AS v_sum
        , SUM( SUM(VALUE) ) OVER(PARTITION BY NO ) AS no_sum
    FROM dataTble
    GROUP BY NO, TAG
) tmpTbl
WHERE no_sum <> v_sum *2

SELECT no
  FROM t
 GROUP BY no
HAVING SUM(DECODE(tag, 'A', val, -val)) != 0
;