将Datagrid数据保存到VB.Net中的SQL Server数据库中

Question

I have a datagrid with data. Column one is a combobox with importers whereas column two is the quantity imported. I want to be able to save this data to the DB irrespective of the user's selection.

Please see my code show below. Can someone help me out?

Dim intReturnValue As Integer = 0

Dim SqlCmd As String = "Update Importer_Balance SET Quantity = Quantity + @Quantity WHERE Importer=@Importer and Product=@product" 

Dim ConnObj As SqlConnection = New SqlConnection(clsGlobals.ConnString)
Dim CmdObj As SqlCommand = New SqlCommand(SqlCmd, ConnObj)

For i = 0 To Me.dgvImporter.RowCount - 1
        CmdObj.Parameters.AddWithValue("@Importer", Me.dgvImporter.Rows(i).Cells(0).Value)
        CmdObj.Parameters.AddWithValue("@Quantity", Me.dgvImporter.Rows(i).Cells(1).Value)
        CmdObj.Parameters.AddWithValue("@Product", cboProductName.SelectedValue)
Next

ConnObj.Open()

intReturnValue = CInt(CmdObj.ExecuteNonQuery())

ConnObj.Close()

If intReturnValue > 0 Then
        MsgBox("You have successfully updated the product table product.", MsgBoxStyle.Information, "")
        ClearForm()
Else
        MsgBox("No Record were inserted", MsgBoxStyle.Exclamation, "")
End If

Answer 1

Inside the loop you add the parameters but don't execute the command, this will work only if you have just one row and results in an error if you have to update more than one row.
You continue to readd the same parameters at each loop to the same command.

Instead move the declaration of the parameters before the loop and inside the loop just set their values and then execute the command.

Dim intReturnValue As Integer = 0
Dim SqlCmd As String = "Update Importer_Balance SET Quantity = Quantity + @Quantity WHERE Importer=@Importer and Product=@product" 

Dim ConnObj As SqlConnection = New SqlConnection(clsGlobals.ConnString)
Dim CmdObj As SqlCommand = New SqlCommand(SqlCmd, ConnObj)
CmdObj.Parameters.Add("@Importer", SqlDbType.Int)
CmdObj.Parameters.Add("@Quantity", SqlDbType.Int)
CmdObj.Parameters.Add("@Product", SqlDbType.Int)
ConnObj.Open()

For i = 0 To Me.dgvImporter.RowCount - 1
    CmdObj.Parameters("@Importer").Value = Convert.ToInt32(Me.dgvImporter.Rows(i).Cells(0).Value)
    CmdObj.Parameters("@Quantity").Value = Convert.ToInt32(Me.dgvImporter.Rows(i).Cells(1).Value)
    CmdObj.Parameters("@Product").Value = Convert.ToInt32(cboProductName.SelectedValue)
    intReturnValue = CInt(CmdObj.ExecuteNonQuery())

Next

Important note. AddWithValue discovers the datatype of the parameter looking at the value passed. This assumption is dangerous and could lead to errors. It is better to use the specialized constructor where you can define the type and the size of the parameter