datetime类型如何计算相差的时间？

Question

例如:
2010-08-30与1988-4-6相差多少天？多少月？
怎么写代码啊？

Answer 1

datediff(day,startdate,enddate)
datediff(month,startdate,enddate)

Answer 2

if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([col1] datetime,[col2] datetime)
insert [tb]
select '2010-08-30','1988-4-6'
goselect
  datediff(dd,col2,col1) as 相差天数,
  datediff(mm,col2,col1) as 相差月数
from
  tb /**
相差天数        相差月数
----------- -----------
8181        268(1 行受影响)
**/

Answer 3

select DATEDIFF(month ,'1988-4-6','2010-08-30'),
    DATEDIFF(day  ,'1988-4-6','2010-08-30')

Answer 4

select datediff(day,'1988-4-6','2010-08-30')--8181 daysselect datediff(month,'1988-4-6','2010-08-30')--268 months