SELECT t1.goods_id AS goods_id1, t2.goods_id AS goods_id2, COUNT(1) AS cnt
FROM
(
  SELECT member_id, goods_id
  FROM sales_slip
  WHERE TD_TIME_RANGE(time, '2013-12-01', '2014-01-01', 'JST')
  GROUP BY member_id, goods_id
) t1,
(
  SELECT member_id, goods_id
  FROM sales_slip
  WHERE TD_TIME_RANGE(time, '2013-12-01', '2014-01-01', 'JST')
  GROUP BY member_id, goods_id
) t2
WHERE t1.member_id = t2.member_id
AND t1.goods_id < t2.goods_id
GROUP BY t1.goods_id, t2.goods_id
ORDER BY cnt DESC