SUM則顯示爲另一列

Question

我有這個表持有幾款產品

而持有從上面

每個產品的訂單另一個表我怎樣才能組合這些表，並獲得每個項目的每個ord_Count的總和，並將其顯示爲另一列，如下所示：

總而言之，我有一個包含不同產品的Items表和一個Orders表，它包含來自Items Table的每個產品的訂單，然後我想要一個查詢結合兩個表並顯示來自Items表中每個項目的庫存。

Answer 1

試試這個：

SELECT SUM(ord_count) AS Item_stock, itm_Code 
FROM YourTable 
GROUP BY itm_Code 

要合併兩個表：

SELECT SUM(B.ord_count) AS Item_stock, B.itm_Code 
FROM YourTable1 AS A 
INNER JOIN YourTable2 AS B 
    ON A.itm_Code = B.itm_Code 
GROUP BY B.itm_Code 

Answer 2

declare @t table (item varchar(20),itemcode varchar(20)) 
insert into @t (item,itemcode)values ('choco','ckschoc'),('chocowafer','wfrchoc'),('chocostrrae','wfrstr') 
declare @tt table (ordcnt int,itemcode varchar(20),dated date) 
insert into @tt (ordcnt,itemcode,dated)values (20,'ckschoc','4/24/2015'),(10,'wfrchoc','4/24/2015'),(15,'wfrstr','4/24/2015') 
,(30,'ckschoc','4/24/2015'),(20,'wfrstr','4/24/2015') 
we can achieve the same result using sub query and corelated join query also 

解決方案

select t.itemcode,p.S from @t t INNER JOIN (
select itemcode,SUM(ordcnt)S from @tt 
GROUP BY itemcode)P 
ON p.itemcode = t.itemcode 
group by t.itemcode,P.s 

select t.itemcode, 
(select SUM(tt.ordcnt)Cnt from @tt tt 
where tt.itemcode = t.itemcode 
group by tt.itemcode)Cnt from @t t