select PCode, PCount=sum(PCount) from tb group by PCount;

------解决方案--------------------

SQL code

--> 测试数据：[test]
if object_id('[test]') is not null drop table [test]
create table [test]([PCode] int,[PCount] int)
insert [test]
select 5,1 union all
select 6,0 union all
select 7,0 union all
select 5,1 union all
select 6,2 union all
select 7,0 union all
select 5,0 union all
select 6,2 union all
select 7,0 union all
select 6,2 union all
select 8,1

select [PCode],SUM([PCount]) as [PCount] 
from test
group by [PCode]
/*
PCode    PCount
5    2
6    6
7    0
8    1
*/