计算另一个表中每个事务中项的数量

Posted 2021-04-28

我在股票部门的公司工作考虑两个出口和股票表，其中出口具有以下属性：

Export{
ExportDate Date not null,
StockID int not null,
Quantity decimal(10, 2),
};

和Stock表具有以下属性：

Stock{
ItemID int primary key,
ItemName nvarchar(MAX).
Exist decimal(15, 2)
};

因此，导出表中的StockID是Stock表格中的ItemID引用，也是当一个记录保存在导出表格中时，它还会根据导出表格中的stockID更新库存存量，这些代码在VB.Net的导出表单中保存按钮，如下所示：

Try
        cmd = New SqlCommand("INSERT INTO Export(ExportDate,StockID,Quantity) VALUES(@ExportDate, @StockID, @Quantity)", con)
        cmd.CommandTimeout = 1000
        cmd.CommandType = CommandType.Text
        cmd.Parameters.AddWithValue("@StockDate", dateTXT.Text)
        cmd.Parameters.AddWithValue("@StockID", comboStockID.SelectedValue)
        cmd.Parameters.AddWithValue("@Quantity", quantityTXT.Text)
        cmd.ExecuteNonQuery()
        MessageBox.show(“Stored”)

    Catch ex As Exception
        MessageBox.Show(“Not stored!” ex.Message)

    End Try





    'Updating stock Exist

        Try
        cmd = New SqlCommand("UPDATE Stock SET Exist = Exist - @quantity
         WHERE ItemID = '" & comboStockID.SelectedValue & "'", con)
        cmd.Parameters.AddWithValue("@quantity", qtyTXT.Text)
        cmd.ExecuteNonQuery()
 MessageBox.show(“Updated!”)

    Catch ex As Exception

        MessageBox.Show(ex.Message)
    End Try

假设股票表格值如下：

ItemID      ItemName      Quantity
  105      Black color      300
  106      Green color      400

但是，当我加入它时，每行显示只有300，它选择如下：

 ItemID      ItemName      Quantity
  105      Black color      300
  106      Green color      300

我想加入Exist of stock with Export table，在每个交易中它必须显示如下：

ExportDate      stockID     Quantity     Exist     
2017/8/24         105          5          295
2017/10/30        105         25          270

帮帮我们，我该怎么办!!!

答案

你可以使用windows函数，这是示例代码：

select exportdate, stockid, quantity, 
sum(pre_balance) over (partition by stockid order by exportdate) as exist  
from 
     (select exportdate, stockid, quantity, -quantity as pre_balance 
      from export 
      union
      select '2017-01-01' as exportdate, itemid as stockid, 
      0 as quantity, exist as pre_balance
      from stock 
      order by exportdate) as sub_query;

这是结果：

exportdate | stockid | quantity | exist  
------------+---------+----------+--------
 2017-01-01 |     105 |        0 | 300.00
 2017-08-24 |     105 |     5.00 | 295.00
 2017-10-30 |     105 |    25.00 | 270.00
 2017-01-01 |     106 |        0 | 400.00

来源表：

latihan=> select * from stock ;
 itemid |  itemname   | exist  
--------+-------------+--------
    105 | Black color | 300.00
    106 | Green color | 400.00
(2 rows)

latihan=> select * from export ;
 exportdate | stockid | quantity 
------------+---------+----------
 2017-08-24 |     105 |     5.00
 2017-10-30 |     105 |    25.00
(2 rows)

这个链接是一个关于windows函数的例子，但在印尼语和postgresql中：

https://github.com/muntaza/Open_Persediaan/blob/master/perhitungan_saldo.md

这是链接到谷歌上的搜索：

https://www.google.com/search?q=windows+function+ms+sql

这个链接关于股票，用英语：

https://callmeranjeet.wordpress.com/2014/09/01/calculating-stock-with-fifo-method-in-sql/