?HackerRank | Symmetric Pairs

HackerRank Symmetric Pairs

SELECT
    P1.X,
    P1.Y
FROM
    Functions AS P1
JOIN
    Functions AS P2
ON
    P1.X = P2.Y
    AND P1.Y = P2.X
GROUP BY
    P1.X,
    P1.Y
HAVING
    COUNT(*) > 1        -- X == Y
    OR P1.X < P1.Y      -- X != Y
ORDER BY
    P1.X ASC;