转载 :http://www.jb51.net/article/129656.htm
DELETE re_question_verify
FROM
re_question_verify,
(
SELECT
min(id) id,
question_id,
verify_id
FROM
re_question_verify
GROUP BY
question_id,
verify_id
HAVING
count(*) > 1
) t2
WHERE
re_question_verify.question_id = t2.question_id
AND re_question_verify.verify_id = t2.verify_id
AND re_question_verify.id > t2.id;