Symmetric Pairs
SELECT A.X, A.Y
FROM FUNCTIONS A INNER JOIN FUNCTIONS B
ON A.X = B.Y AND A.Y = B.X
GROUP BY A.X, A.Y
HAVING COUNT(A.X) > 1 OR A.X < A.Y
ORDER BY A.X
SELECT A.X, A.Y
FROM FUNCTIONS A INNER JOIN FUNCTIONS B
ON A.X = B.Y AND A.Y = B.X
GROUP BY A.X, A.Y
HAVING COUNT(A.X) > 1 OR A.X < A.Y
ORDER BY A.X
