if object_id('tempdb.dbo.#tb') is not null drop table #tb
go
create table #tb (年月日 datetime,省份代码 int,城市代码 int,客户代码 int,购进量 int)
insert into #tb
select '20100101',1,11,111,0 union all
select '20100101',1,11,111,0 union all
select '20100101',1,11,112,1 union all
select '20100201',1,11,111,0 union all
select '20100201',1,11,111,0 union all
select '20100201',1,11,112,1 union all
select '20100301',1,11,111,2 union all
select '20100301',1,11,111,0 union all
select '20100301',1,11,112,1 union all
select '20100401',1,11,111,0 union all
select '20100401',1,11,111,0 union all
select '20100401',1,11,112,1 union all
select '20100501',1,11,111,0 union all
select '20100501',1,11,111,0 union all
select '20100501',1,11,112,1 union all
select '20100601',1,11,111,0 union all
select '20100601',1,11,111,0 union all
select '20100601',1,11,112,1 union all
select '20100701',1,11,111,0 union all
select '20100701',1,11,111,0 union all
select '20100701',1,11,112,1 union all
select '20100801',1,11,111,0 union all
select '20100801',1,11,111,0 union all
select '20100801',1,11,112,1 union all
select '20100901',1,11,111,0 union all
select '20100901',1,11,111,0 union all
select '20100901',1,11,112,1 union all
select '20101001',1,11,111,0 union all
select '20101001',1,11,111,0 union all
select '20101001',1,11,112,1 union all
select '20101101',1,11,111,0 union all
select '20101101',1,11,111,0 union all
select '20101101',1,11,112,1 union all
select '20101201',1,11,111,0 union all
select '20101201',1,11,111,0 union all
select '20101201',1,11,112,1

select 省份代码,城市代码,count(distinct 客户代码 ) as N
from #tb t
where month(年月日)>2 and 购进量>0
 and not exists(select 1 from #tb where 省份代码=t.省份代码 and 城市代码=t.城市代码 and 客户代码=t.客户代码 and month(年月日)<=2 and 购进量>0)
group by 省份代码,城市代码


省份代码        城市代码        N
----------- ----------- -----------
1           11          1

(1 行受影响)

------解决方案--------