ماهى عملية الضرب داخل sql - نسخة قابلة للطباعة

كود :
 Public Sub InsertStore()

        '****************************دا عشان مخزن الماركت وبالاخص تقرير المباع يوميا

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        For i As Integer = 0 To Dgv_prd2.Rows.Count - 1

            Dim _Qty As String = Dgv_prd2.Rows(i).Cells(4).Value

            Dim _price As String = Dgv_prd2.Rows(i).Cells(5).Value

            Dim cmd1 As New SqlCommand("select * from report_Store where Prd_ID =@Prd_ID ", Con)

            cmd1.Parameters.Clear()

            cmd1.Parameters.AddWithValue("@Prd_ID", SqlDbType.Int).Value = Dgv_prd2.Rows(i).Cells(1).Value

            Dim dt As New DataTable

            Dim adp As New SqlDataAdapter(cmd1)

            adp.Fill(dt)

            If dt.Rows.Count > 0 Then

                Dim Cmd2 As New SqlCommand

                With Cmd2

                    .Connection = Con

                    .CommandType = CommandType.Text

                    .CommandText = "Update report_Store Set Qty = Qty + " & _Qty & " , BuyPrice = (Qty + " & _Qty & ") * SellPrice Where Prd_ID = @Prd_ID"

                    .Parameters.Clear()

                    .Parameters.AddWithValue("@Prd_ID", SqlDbType.Int).Value = Dgv_prd2.Rows(i).Cells(1).Value

                End With

                If Con.State = 1 Then Con.Close()

                Con.Open()

                Cmd2.ExecuteNonQuery()

                Con.Close()

                Cmd2 = Nothing

            Else

                Dim Cmd3 As New SqlCommand

                With Cmd3

                    .Connection = Con

                    .CommandType = CommandType.Text

                    .CommandText = "Insert Into report_Store ( Prd_ID,Qty,BuyPrice,SellPrice)values(@Prd_ID,@Qty,@BuyPrice,@SellPrice)"

                    .Parameters.Clear()

                    .Parameters.AddWithValue("@Prd_ID", SqlDbType.Int).Value = Dgv_prd2.Rows(i).Cells(1).Value

                    .Parameters.AddWithValue("@Qty", SqlDbType.VarChar).Value = _Qty

                    .Parameters.AddWithValue("@BuyPrice", SqlDbType.Decimal).Value = _price * _Qty

                    .Parameters.AddWithValue("@SellPrice", SqlDbType.Decimal).Value = Dgv_prd2.Rows(i).Cells(5).Value

                End With

                If Con.State = 1 Then Con.Close()

                Con.Open()

                Cmd3.ExecuteNonQuery()

                Con.Close()

                Cmd3 = Nothing

            End If

        Next



    End Sub