SQL Server 2005：如何减去 6 个月
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SQL Server 2005: how to subtract 6 month
提问by skaeff
I have a date, suppose today date
我有个约会，假设今天约会
declare @d datetime
set @d = '20101014'
I need
我需要
select @d - <six month>
where is the real number of days that contains last six month, beginning from @d.
哪里是包含过去六个月的实际天数，从@d 开始。
回答by Alex Bagnolini
回答by skaeff
Also check this up (developing this theme):
还要检查一下（开发这个主题）：
i need to choose the algorythm depending on the condition - if there are as many days between two dates as in 6 month (ago from the last date).
我需要根据条件选择算法 - 如果两个日期之间的天数与 6 个月一样多（从最后一个日期开始）。
I did it in this way:
我是这样做的：
case
when
DATEDIFF(day, DATEADD(month, -6, @pDateEnd), @pDateEnd)
>
DATEDIFF(day, @pDateBegin, @pDateEnd)
then 'there is no 6-month difference between two dates'
else 'there is 6-month difference ore more between two dates'
end
