日期是怎么计算的，关于months_between()?

水晶化了

select months_between('22-jul-2003','21-may-2003') from dual;
result:2.03225806
select months_between('21-may-2003','22-jul-2003') from dual;
result: -2.0322581
这两个结果的绝对值不同，如果the first date later than the last one
result=date1-date2
如果the first date earlier than the last one
result=?

nyfor

这是显示时的舍入误差，实际上是一样的。
set numformat 9.00000000000000000000000000000000000
alter session set nls_date_format = 'yyyy-mm-dd';

select months_between('2003-05-22','2003-04-21') from dual;
select months_between('2003-04-21','2003-05-22') from dual;