update a set col2=case when (select sum(col2) from tb 
                         where col1=a.col1 and 时间<=a.时间)<=60 then 0 
         else col2-(select sum(col2) from tb where col1=a.col1 and 时间<=a.时间) end
from tb a where col1 in ('a','b')

------解决方案--------------------

SQL code

if object_id('tb','U') is not null
   drop table tb
go
create table tb
(
 c1 varchar(10),
 c2 int
)
go
insert into tb
select 'A',50 union all
select 'B',30 union all
select 'A',10 union all
select 'B',15 union all
select 'C',35 union all
select 'B',40
go
with cte as
(
select c1,c2,row=row_number() over(order by getdate()) from tb
)
update a set c2=b.c2 from (select *,row=row_number() over(order by getdate()) from tb) a inner join 
(
select c1,row, c2=case 
                    when (select sum(c2) from cte where c1=t1.c1 and row<=t1.row)-60<0 then 0 else (select sum(c2) from cte where c1=t1.c1 and row<=t1.row)-60 end 
from cte t1 where c1='B' or C1='A'
) b on a.row=b.row
/*
c1         c2
---------- -----------
A          0
B          0
A          0
B          0
C          35
B          25

(6 行受影响)

*/

------解决方案--------------------
把表结构和数据列出来，还有你想要的结果也列出来


------解决方案--------------------
在之后往里插入数据的时候要做一个插入的判断：

SQL code

--对已有的 id xtype 类型要做累加或减
update tb
set num = num + @value
where id = @id and xtype = @xtype

--@value是插入的num值，@id @xtype 是表中对应的id xtype

--对没有在表中存在的id xtype可以直接插入
insert into tb
select @id,@value,@xtype,@stime

------解决方案--------------------
4楼的不就是你想要的结果吗


------解决方案--------------------
探讨

表记录如下：
A   50
B   30
A   10
B   15
C   35
B   40

就是每个人存入一笔款，有一条记录：

现在要把a、b的账户同时扣掉60，怎么写sql语句呢？？？