db2 怎么计算两个时间相差多少个月。如2015-10-10 和2014-1-12

SELECT
  timestampdiff (256, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔年",
  timestampdiff (128, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔季度",
  timestampdiff (64, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔月",
  timestampdiff (32, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔周",
  timestampdiff (16, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔日",
  timestampdiff (8, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔时",
  timestampdiff (4, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔分",
  timestampdiff (2, char(timestamp('2013-12-30 20:30:30') - timestamp('2001-09-26 15:24:23'))) AS "间隔秒"
FROM SYSIBM.SYSDUMMY1;