SQL запрос для выбора несовпадения?
LEFT JOIN и IS NULL
-- Используя WHERE NOT EXISTS
SELECT * 
FROM QEEN
WHERE NOT EXISTS (
	SELECT ID FROM QEEN REVERSE_QEEN WHERE REVERSE_QEEN.A = QEEN.B AND REVERSE_QEEN.B = QEEN.A
);

-- Используя LEFT JOIN
SELECT QEEN.* 
FROM QEEN
LEFT JOIN QEEN REVERSE_QEEN ON REVERSE_QEEN.A = QEEN.B AND REVERSE_QEEN.B = QEEN.A
WHERE REVERSE_QEEN.ID IS NULL;

-- Просто извращение, но тоже должно работать :)
WITH ALL_QEEN AS (
	SELECT ID, A, B, 1 T FROM QEEN
  	UNION ALL
  	SELECT ID, B, A, 2 T FROM QEEN
) SELECT 
	MIN(ID) ID, A, B
FROM ALL_QEEN
GROUP BY A, B
HAVING COUNT(*) = 1 AND MIN(T) = 1;

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