SQL query to select mismatch?

Question

SQL

There is a table QEEN
ID AB
1 22 32
2 22 55
3 32 22
4 32 77

How to select only ID=2 and ID=4 with a SELECT query, that is, select an ID where there are no matches in A and B and vice versa B and A for different rows.

Answer 1

-- 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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Answer 2

LEFT JOIN and IS NULL