SELECT left.keycol as onlyleft
FROM left LEFT JOIN right ON left.keycol = right.keycol
WHERE right.keycol IS NULL


SELECT right.keycol as onlyright
FROM right LEFT JOIN left ON left.keycol = right.keycol
WHERE left.keycol IS NULL


SELECT right.keycol as onlyright
FROM right INNER JOIN left ON left.keycol = right.keycol