if exists(select 1 from sys.objects where object_id=object_id('tab'))
begin
drop table tab
end
go
create table tab(item int, date datetime, temp int)
insert tab select 10,'2006-01-01',0
union all select 10,'2006-02-01',0
union all select 10,'2006-03-01',0
union all select 20,'2006-01-01',0
union all select 20,'2006-02-01',0
union all select 30,'2006-01-01',0
union all select 30,'2006-02-01',0
union all select 30,'2006-03-01',0
union all select 30,'2006-04-01',0
union all select 30,'2006-05-01',0
go
select *,row_number() over(partition by item order by date ) as t from tab
go
--结果
/**//*
item date temp t
----------- ----------------------- ----------- --------------------
10 2006-01-01 00:00:00.000 0 1
10 2006-02-01 00:00:00.000 0 2
10 2006-03-01 00:00:00.000 0 3
20 2006-01-01 00:00:00.000 0 1
20 2006-02-01 00:00:00.000 0 2
30 2006-01-01 00:00:00.000 0 1
30 2006-02-01 00:00:00.000 0 2
30 2006-03-01 00:00:00.000 0 3
30 2006-04-01 00:00:00.000 0 4
30 2006-05-01 00:00:00.000 0 5
(10 行受影响)
*/