sql数据按月叠加？

Question

aa,2008-02,100
aa,2008-03,200
bb,2008-03,100变
aa,2008-02,100
aa,2008-03,300
bb,2008-03,100
这样？

Answer 1

create table tb(projID varchar(20),planmonth varchar(10),monthjzl int)
insert into tb select 'aa','2008-02',100
insert into tb select 'aa','2008-03',200
insert into tb select 'bb','2008-03',100select projid,planmonth,
monthjzl=(select sum(monthjzl) from tb where projID=t.projID and cast(planmonth+'-01' as datetime)<=cast(t.planmonth+'-01' as datetime)) 
from tb t
projid planmonth monthjzl
aa 2008-02 100
aa 2008-03 300
bb 2008-03 100
给你加了'-01',免得直接比较误差