SELECT Latest 取得最近的信息
SELECT beyond_id, year_month, detail_infoFROM t_beyond bINNER JOIN( SELECT beyond_id, MAX(year_month) AS year_month FROM t_beyond WHERE year_month <= '20100912' GROUP BY beyond_id) mON b.beyond_id = m.beyond_idAND b.year_month = m.year_month?