mysql多字段组合删除重复行

DELETE
FROM boll_param
WHERE id in (
  SELECT a.id
  FROM (
         SELECT id
         FROM boll_param
         WHERE (symbol, time_frame, ma, k, std, N, 回测起始日期, 回测结束日期, 交易方向) IN (
           SELECT symbol,
                  time_frame,
                  ma,
                  k,
                  std,
                  N,
                  回测起始日期,
                  回测结束日期,
                  交易方向
           FROM boll_param
           GROUP BY symbol, time_frame, ma, k, std, N, 回测起始日期, 回测结束日期, 交易方向
           HAVING count(*) > 1
         )
           AND id NOT IN (
           SELECT minid
           FROM (
                  SELECT min(id) AS minid
                  FROM boll_param
                  GROUP BY symbol, time_frame, ma, k, std, N, 回测起始日期, 回测结束日期, 交易方向
                  HAVING count(*) > 1
                ) dt
         )) a
)