MYSQL 달력 제작

SELECT ym
  , MIN(CASE dw WHEN 1 THEN d END) Sun
  , MIN(CASE dw WHEN 2 THEN d END) Mon
  , MIN(CASE dw WHEN 3 THEN d END) Tue
  , MIN(CASE dw WHEN 4 THEN d END) Wed
  , MIN(CASE dw WHEN 5 THEN d END) Thu
  , MIN(CASE dw WHEN 6 THEN d END) Fri
  , MIN(CASE dw WHEN 7 THEN d END) Sat
FROM (SELECT date_format(dt,'%Y%m') ym
        , Week(dt) w
        , Day(dt) d
        , DayofWeek(dt) dw
      FROM (SELECT CONCAT(y, '0101') + INTERVAL a*100 + b*10 + c DAY dt
            FROM (SELECT 0 a
                  UNION ALL SELECT 1                  UNION ALL SELECT 2                  UNION ALL SELECT 3                 ) a
              , (SELECT 0 b
                 UNION ALL SELECT 1                 UNION ALL SELECT 2                 UNION ALL SELECT 3                 UNION ALL SELECT 4                 UNION ALL SELECT 5                 UNION ALL SELECT 6                 UNION ALL SELECT 7                 UNION ALL SELECT 8                 UNION ALL SELECT 9                ) b
              , (SELECT 0 c
                 UNION ALL SELECT 1                 UNION ALL SELECT 2                 UNION ALL SELECT 3                 UNION ALL SELECT 4                 UNION ALL SELECT 5                 UNION ALL SELECT 6                 UNION ALL SELECT 7                 UNION ALL SELECT 8                 UNION ALL SELECT 9                ) c
              , (SELECT '2015' y) d
            WHERE a*100 + b*10 + c < DayOfYear(CONCAT(y, '1231'))
           ) a
     ) a
GROUP BY ym, w
;