--我的是繫體,你改下就好了
select 商品編號,
    sum(decode(所在倉庫,'1',商品數量,0)) as 總量
from t
group by 商品編號,所在倉庫;

------解决方案--------------------
create table testTab
(
 id varchar(10),
 num number,
 ran number
)

insert into testTab (id,num,ran) values('a',1,1);
 insert into testTab (id,num,ran) values('a',2,1);
 insert into testTab (id,num,ran) values('b',2,2);
 insert into testTab (id,num,ran) values('a',2,2);
    
    
 select id,
     sum(decode(ran,ran,num)) as 总量,
     ran 所在仓库
 from testTab  
 group by id,ran