VB สอบถามปัญหาครับ ผมต้องการให้มีการวนลูป เพื่อเพิ่ม หรือ อัพเดทไปที่ database แต่มีเงื่อนไขคือ ถ้ามีแล้ว จะแก้ไขค่าเข้าไป แต่ถ้าไม่มีจะเพิ่มเข้าไปใหม่ทั้งหมด ติดปัญหาตรง การวนลูป

 Private Sub Button2_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        sql = "insert into savegoods_production(save_pro_id,pro_id,goods_name,goods_unit,goods_amount,goods_price,emp_name,emp_tell,date_save) values "
        Dim i As Integer = Me.ListView1.Items.Count - 1
        For j As Integer = 0 To i
            Dim po_id As String = Me.ListView1.Items(j).SubItems(1).Text
            Dim goods_name As String = Me.ListView1.Items(j).SubItems(2).Text
            Dim goods_unit As String = Me.ListView1.Items(j).SubItems(3).Text
            Dim goods_amount As Double = Me.ListView1.Items(j).SubItems(4).Text
            Dim goods_price As Double = Me.ListView1.Items(j).SubItems(5).Text
            Dim em_name As String = Me.em_name.Text
            Dim em_tell As String = Me.em_tell.Text
            Dim save_date As Date = Me.lbl_date_now.Text
            If j = i Then
                sql &= String.Format("('{0}','{1}','{2}','{3}','{4}','{5}','{6}','{7}','{8}')", Me.lbl_save_id.Text, po_id, goods_name, goods_unit, goods_amount, goods_price, em_name, em_tell, save_date)
            Else
                sql &= String.Format("('{0}','{1}','{2}','{3}','{4}','{5}','{6}','{7}','{8}') ,", Me.lbl_save_id.Text, po_id, goods_name, goods_unit, goods_amount, goods_price, em_name, em_tell, save_date)
            End If

        Next

        cmd = New SqlClient.SqlCommand(sql, cn)
        If cmd.ExecuteNonQuery = 0 Then
            MsgBox("ไม่สามารถบันทึกได้")
        Else
            MsgBox("บันทึกสำเร็จ")

            Dim p As Integer = Me.ListView1.Items.Count - 1
            For j As Integer = 0 To p


                Dim goods_name As String = Me.ListView1.Items(j).SubItems(2).Text
                Dim goods_unit As String = Me.ListView1.Items(j).SubItems(3).Text
                Dim goods_amount As Double = Me.ListView1.Items(j).SubItems(4).Text
                Dim goods_price As Double = Me.ListView1.Items(j).SubItems(5).Text
                'If j = p Then

                Dim sql2 As String = "select goods_name from stock_goods where goods_name ='" & goods_name & "'"
                Dim cmd As New SqlCommand(sql2, cn)
                Dim dr As SqlDataReader
                dr = cmd.ExecuteReader
                If dr.Read >= 0 Then
                    sql = "insert into stock_goods(goods_name,goods_unit,goods_amount,goods_price) values "
                    If j = p Then
                        sql &= String.Format("('{0}','{1}','{2}','{3}')", goods_name, goods_unit, goods_amount, goods_price)
                    Else
                        sql &= String.Format("('{0}','{1}','{2}','{3}') ,", goods_name, goods_unit, goods_amount, goods_price)
                    End If

                Else
                    sql = "update stock_goods set goods_amount = goods_amount+ " & goods_amount & " where goods_name='" & goods_name & "'"
                End If
                'End If

            Next

            cmd = New SqlClient.SqlCommand(sql, cn)
            If cmd.ExecuteNonQuery = 0 Then
                MsgBox("ไม่สามารถบันทึกได้")
            Else
                MsgBox("บันทึกสำเร็จ")
            End If
        End If
    End Sub

Dim p As Integer = Me.ListView1.Items.Count - 1
            For j As Integer = 0 To p


                Dim goods_name As String = Me.ListView1.Items(j).SubItems(2).Text
                Dim goods_unit As String = Me.ListView1.Items(j).SubItems(3).Text
                Dim goods_amount As Double = Me.ListView1.Items(j).SubItems(4).Text
                Dim goods_price As Double = Me.ListView1.Items(j).SubItems(5).Text
                'If j = p Then

                Dim sql2 As String = "select goods_name from stock_goods where goods_name ='" & goods_name & "'"
                Dim cmd As New SqlCommand(sql2, cn)
                Dim dr As SqlDataReader
                dr = cmd.ExecuteReader
                If dr.Read >= 0 Then
                    sql = "insert into stock_goods(goods_name,goods_unit,goods_amount,goods_price) values "
                    If j = p Then
                        sql &= String.Format("('{0}','{1}','{2}','{3}')", goods_name, goods_unit, goods_amount, goods_price)
                    Else
                        sql &= String.Format("('{0}','{1}','{2}','{3}') ,", goods_name, goods_unit, goods_amount, goods_price)
                    End If

                Else
                    sql = "update stock_goods set goods_amount = goods_amount+ " & goods_amount & " where goods_name='" & goods_name & "'"
                End If
                'End If

            Next

            cmd = New SqlClient.SqlCommand(sql, cn)
            If cmd.ExecuteNonQuery = 0 Then
                MsgBox("ไม่สามารถบันทึกได้")
            Else
                MsgBox("บันทึกสำเร็จ")
            End If