SELECT
  i.itemid,
  CONCAT(
    GROUP_CONCAT(f.channelcode),
    '-',
    GROUP_CONCAT(DISTINCT IF(f.type = 1, '白', '黑'))
  ) channelcode
FROM
  iteminfo i
  left JOIN item_channelinfo f ON i.itemid = f.itemid
where
  i.itemid in (7084848)
GROUP BY
  i.itemid