Question

我需要一个解决方案。我想从一个表中减去/添加一个字段值与另一个表。我提供了详细信息。

我有两张桌子（相同的结构）。

表1 - purchase字段：id, purchase_from, product_name, quantity, rate

表2 - sales字段：id, sale_to, product_name, quantity, rate

现在我想将数量从purchase表减去sales表，并将数据显示到数据网格视图中。

我试过了，但失败了。我已经为您提供了代码段。

Dim PurchasePrdName, SalesPrdName As String Dim PurchaseQty, SalesQty As Double

Private Sub LoadPurchase()

    Try
        OpenConnection()
        Dim dcommand As New MySqlCommand
        Dim qry As String = "SELECT ProductName,SUM(Quantity) FROM stockitems GROUP BY ProductId"
        dcommand.Connection = conn
        dcommand.CommandText = qry

        Dim dbread As MySqlDataReader = dcommand.ExecuteReader
        DataGridView1.Rows.Clear()
        While dbread.Read
            If dbread.HasRows Then
                PurchasePrdName = dbread("ProductName").ToString
                PurchaseQty = dbread("SUM(Quantity)").ToString
            End If
        End While
        dbread.Close()
    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        CloseConnection()
    End Try

End Sub

Private Sub LoadSales()

    Try
        OpenConnection()
        Dim dcommand As New MySqlCommand
        Dim qry As String = "SELECT SUM(Quantity) FROM salesitems WHERE ProductName='" & PurchasePrdName & "' GROUP BY ProductId"
        dcommand.Connection = conn
        dcommand.CommandText = qry

        Dim dbread As MySqlDataReader = dcommand.ExecuteReader
        DataGridView1.Rows.Clear()
        While dbread.Read
            If dbread.HasRows Then
                SalesQty = dbread("SUM(Quantity)").ToString
            End If
        End While
        dbread.Close()
    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        CloseConnection()
    End Try

    End Sub

然后将此数据加载到DataGridView ...

Private Sub LoadData() Try LoadPurchase() LoadSales() Dim PrdName As String = PurchasePrdName Dim Qty As Double = PurchaseQty - SalesQty DataGridView1.Rows.Add(PrdName, Qty) DbGridCustomize() Catch ex As Exception MsgBox(ex.Message) End Try End Sub

但它只显示表中的一个产品。我混淆了为什么!!!

你能帮我解决这个问题吗？

我非常感谢你

Answer 1

您只向网格添加一行，这是分配给PurchasePrdName的产品。您需要将一组值绑定到网格，或者需要迭代一组值。看起来好像你在这里所做的就是为变量分配一个值，然后在网格中添加一行：

DataGridView1.Rows.Add(PrdName, Qty)

编辑：

我会将您的变量PurchasePrdName和SalePrdName更改为集合，因为您希望在此处存储多个值。

Private PurchasePrdName As Dictionary(Of String, Double)
Private SalesPrdName As Dictionary(Of String, Double)

然后当你加载购买和销售时，你会做这样的事情：

While dbread.Read
    If dbread.HasRows Then
        PurchasePrdName.Add(dbread("ProductName").ToString, dbread("SUM(Quantity)"))
    End If
End While

然后，当您进行销售时，您需要遍历产品词典以提取每个产品名称。您可以存储销售数量，但您也可以同时计算差额并存储。最好创建一个包含所有项目的类，并将它们存储在一个字典中。

在销售负载中，您将迭代字典

For Each product In PurchasePrdName.Keys
    Dim qry As String = "SELECT SUM(Quantity) FROM salesitems WHERE ProductName='" & product & "' GROUP BY ProductId"

    dcommand.CommandText = qry

    Dim dbread As MySqlDataReader = dcommand.ExecuteReader
    DataGridView1.Rows.Clear()
    While dbread.Read
        If dbread.HasRows Then
            SalesPrdName.Add(product, PurchasePrdName(product) - Double.Parse(dbread("SUM(Quantity)")))
        End If
    End While

    dbread.Close()

Next

最后你还想在循环中添加行......

For Each product In SalesPrdName.Keys
    DataGridView1.Rows.Add(product, SalesPrdName(product))
Next

您可能希望更改变量名称以反映其新含义等。如果您想存储销售数量，那么我建议您使用一个字典，其中产品名称为键，类为值。该课程将包括产品名称，产品数量，销售数量以及两者之间的差异。

计算两个不同表中的字段并在DatagridView中显示

1 个答案: