Mysql 如何将一个表列值减去其他表列值

我有两张桌子存货和销售

股票

出售

我想要减去数量后的结果

股票

---

救命啊

如果要将结果存储在mysql中，可以（使用关系名称）更新

或者使用id作为关系

update Stock as a
inner join Sale as b on a.id = b.id 
set a.Qty = a.Qty -b.Qty

或者，如果你只是想要一个选择，你可以

select a.id, a.name, a.size,  a.Qty -b.Qty as qty
from fromStock as a 
inner join Sale as b on a.id = b.id 

在sqlite中，不允许使用内部联接进行更新，因此使用子选择

update Stock 
set Qty = (    select Stock.Qty -Sale.Qty from Stock
                Inner join Sale on  Sale.name = Stock.name )
WHERE
EXISTS (
    SELECT *
    from Stock
                Inner join Sale on  Sale.name = Stock.name 
)

---

如果您想将结果存储在mysql中，您可以（使用关系的名称）更新

或者使用id作为关系

update Stock as a
inner join Sale as b on a.id = b.id 
set a.Qty = a.Qty -b.Qty

或者，如果你只是想要一个选择，你可以

select a.id, a.name, a.size,  a.Qty -b.Qty as qty
from fromStock as a 
inner join Sale as b on a.id = b.id 

在sqlite中，不允许使用内部联接进行更新，因此使用子选择

update Stock 
set Qty = (    select Stock.Qty -Sale.Qty from Stock
                Inner join Sale on  Sale.name = Stock.name )
WHERE
EXISTS (
    SELECT *
    from Stock
                Inner join Sale on  Sale.name = Stock.name 
)

---

您可以通过

id

和

name

连接表，然后简单地减去

Qty

值。添加名称以提高可读性

SELECT ST.id, ST.Name, ST.size, (ST.Qty - SA.Qty) AS Qty
FROM Stock ST
INNER JOIN Sale SA ON SA.id = ST.id AND SA.Name = ST.Name

如果不需要通过

Name

加入，则只能通过

id

as加入

SELECT ST.id, ST.Name, ST.size, (ST.Qty - SA.Qty) AS Qty
FROM Stock ST
INNER JOIN Sale SA ON SA.id = ST.id

---

更新SQLite的

UPDATE Stock 
SET Qty = ( SELECT ST.Qty - SA.Qty
            FROM Stock ST
            INNER JOIN Sale SA ON SA.id = ST.id )
WHERE id IN (SELECT id FROM Stock )

---

从

获取引用您可以通过

id

和

name

加入表，然后简单地减去

数量

值。添加名称以提高可读性

SELECT ST.id, ST.Name, ST.size, (ST.Qty - SA.Qty) AS Qty
FROM Stock ST
INNER JOIN Sale SA ON SA.id = ST.id AND SA.Name = ST.Name

如果不需要通过

Name

加入，则只能通过

id

as加入

SELECT ST.id, ST.Name, ST.size, (ST.Qty - SA.Qty) AS Qty
FROM Stock ST
INNER JOIN Sale SA ON SA.id = ST.id

---

更新SQLite的

UPDATE Stock 
SET Qty = ( SELECT ST.Qty - SA.Qty
            FROM Stock ST
            INNER JOIN Sale SA ON SA.id = ST.id )
WHERE id IN (SELECT id FROM Stock )

从

获取参考请尝试以下操作：

SELECT Stock.id, Stock.Name, Stock.size, (Stock.Qty - Sale.Qty) AS Qty
FROM Stock
INNER JOIN Sale ON Sale.id = Stock.id

试试这个：

SELECT Stock.id, Stock.Name, Stock.size, (Stock.Qty - Sale.Qty) AS Qty
FROM Stock
INNER JOIN Sale ON Sale.id = Stock.id

使用下面的查询

Select table.id,table.name,table.size,sum(table.qty) from
(Select id,name,size,qty from stock 
Union
Select id,name,size,qty*-1 from sale) as table group by table.id,table.name,table.size

使用下面的查询

Select table.id,table.name,table.size,sum(table.qty) from
(Select id,name,size,qty from stock 
Union
Select id,name,size,qty*-1 from sale) as table group by table.id,table.name,table.size

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你在使用什么数据库？MySQL和SQLite不是一回事。MySQL和SQLite都是。你用的是什么数据库？MySQL和SQLite不是一回事。MySQL和SQLite都是..@10086 weel so。。你可以很容易地得到你的结果。我可以在SQLite中做什么？@10086 weel-so。。你可以很容易地得到你的结果我可以在SQLite中做什么？