比如字段N是唯一索引:
declare @tt datetime
select top 1 @tt=T
from 表a
order by N desc
insert 表a(T) values(dateadd(second,datediff(second,@tt,getdate()),getdate()))
declare @tt datetime
select top 1 @tt=T
from 表a
order by N desc
insert 表a(T) values(dateadd(second,datediff(second,@tt,getdate()),getdate()))
select top 3 @n1=N from ta
select top 4 @n2=N from tainsert ta select @n2-@n1,getdate()
(select top 1 N from ta order by T desc)
-
(
select top 1 N from
(select 2 * from ta order by T desc) x
order by T asc
),
getdate()
(
select N From ta
where convert(varchar(10), T, 120) = convert(varchar(10), getdate(), 120)
)
-
(
select top 1 N From ta where convert(varchar(10), T, 120) <> convert(varchar(10), getdate(), 120)
order by T desc
), getdate()