日期型字段相减的问题

[LNSPRITE]

现有两个字段都是DATETIME型,想求出它们之间相差的天数.
例: A DATETIME
B DATETIME
SELECT (A-B)AS AA FROM BB

[yokel]

看看这个就知道了
select datediff(day,'2002-1-18','2002-1-21')

[yokel]

用用这个就知道怎么办了
select datediff(day,'2002-1-18','2002-1-21')

[pengdali]

select datediff(day,'2001-1-1','2002-1-1') 天
select datediff(month'2001-1-1','2002-1-1') 月
select datediff(year,'2001-1-1','2002-1-1') 年


你的：

select datediff(day,b,a) aa from bb

[chao778899]

datediff(day,day1,day2)

[LNSPRITE]

如果两个字段不在同一个月,那怎么办呢?

[dafu71]

SELECT datediff(dd,B,A) AS AA FROM BB

[dafu71]

SELECT abs(datediff(dd,B,A)) AS AA FROM BB

[rs_net]

用datediff一样可以求得，你看看datediff的帮助就知道datediff是干什么的了

[zjcxc]

其实你的语句本身就可以实现你的目的.