Sql空值在一列分區

Question

我只是浪費這個Sql Transact後面的兩到三個Hourse，並且混淆了空值Skip。

我有兩個表如下圖所示：

Table 1: AccountMast 
companyID accname   category 
102  PURCHASE ACCOUNT Purchase Account 
102  SALES ACCOUNT  Sales Account 

Table2: Legder 

companyID name    
102  PURCHASE ACCOUNT   
102  SALES ACCOUNT  

我有如下加入吧：

select 
case 
when a.catagory='Purchase Account' then 
l.name 
end as PurchaseAccount, 
case 
when a.catagory = 'Sales Account' then 
l.name 
end as SalesAccount 
from ledger l join accountmast a 
on l.companyID=a.companyID 
and l.name = a.accname 
where l.companyID=102 
and a.catagory='Purchase Account' or a.catagory='Sales Account' 
group by l.name,a.catagory 

結果是：

PurchaseAccount  SaleAccount 
PURCHASE ACCOUNT NULL 
NULL    SALES ACCOUNT 

，但我想結果一樣：

PurchaseAccount  SaleAccount 
PURCHASE ACCOUNT SALES ACCOUNT 

如何做到這一點？

Answer 1

刪除您GROUP BY條款：

select 
    max(case when a.catagory = 'Purchase Account' then l.name end) as PurchaseAccount, 
    max(case when a.catagory = 'Sales Account' then l.name end) as SalesAccount 
from ledger l 
join accountmast a 
on l.companyID = a.companyID and l.name = a.accname 
where l.companyID=102 and a.catagory IN ('Purchase Account', 'Sales Account')