ทำอย่างไรให้เพิ่มข้อมูลได้หลายครั้งค่ะ เมื่อกดเพิ่มแล้วก็สามารถเพิ่มข้อมูลได้ แต่เมื่อต้องการเพิ่มซักรอบที่ 3 มันจะขึ้น error ตามรูปอ่ะค่ะ

 If stout.Text <= stqty1.Text Then
            If stqty1.Text < stout.Text Then
                MessageBox.Show("ยอดคงเหลือน้อยกว่ายอดที่ต้องการเบิกกรุณาเบิกสินค้า Lot แรกให้หมดก่อน", "ผลการตรวจสอบ", MessageBoxButtons.OK, MessageBoxIcon.Warning)
                stout.Focus()
                Exit Sub
            End If
            sql = "Insert Into outdetail (outcode,stcode,stout,cost,outfordept,outfordocno,stat) "
            sql &= " Values ('" & outcode.Text & "',"
            sql &= "'" & Stname.SelectedValue & "',"
            sql &= "'" & stout.Text & "',"
            sql &= "'" & Cost.Text & "',"
            sql &= "'" & outdept.SelectedValue & "',"
            sql &= "'" & outfordocno.Text & "',"
            sql &= "1)"
            sql &= " Insert Into stdetail (stcode,stdate,stout,cost,cmname,cmdept,remark,ststat)"
            sql &= " Values ('" & Stname.SelectedValue & "',"
            sql &= "'" & outdate.Value.ToString("s") & "',"
            sql &= "'" & stout.Text & "',"
            sql &= "'" & Cost.Text & "',"
            sql &= "'" & outname.Text & "',"
            sql &= "'" & outdept.SelectedValue & "',"
            sql &= "'" & outfordocno.Text & "',"
            sql &= "1)"
            sql &= " Update stock"
            sql &= " Set stqty=stqty-'" & stout.Text & "',"
            sql &= " stqty1=stqty1-'" & stout.Text & "'"
            sql &= " Where (stcode='" & Stname.SelectedValue & "')"
            sql &= " Update stdetail "
            sql &= " Set stbal='" & stqty.Text - stout.Text & "'"
            sql &= " Where (stcode='" & Stname.SelectedValue & "')"
            sql &= " And (stdate='" & outdate.Value.ToString("s") & "')"
        Else
            sql = " Insert Into outdetail (outcode,stcode,stout,cost,outfordept,outfordocno,stat)"
            sql &= " Values ('" & outcode.Text & "',"
            sql &= "'" & Stname.SelectedValue & "',"
            sql &= "'" & stout.Text & "',"
            sql &= "'" & Cost.Text & "',"
            sql &= "'" & outdept.SelectedValue & "',"
            sql &= "'" & outfordocno.Text & "',"
            sql &= "1)"
            sql &= " Insert Into stdetail (stcode,stdate,stout,cost,cmname,cmdept,remark,ststat)"
            sql &= " Values ('" & Stname.SelectedValue & "',"
            sql &= "'" & outdate.Value.ToString("s") & "',"
            sql &= "'" & stout.Text & "',"
            sql &= "'" & Cost.Text & "',"
            sql &= "'" & outname.Text & "',"
            sql &= "'" & outdept.SelectedValue & "',"
            sql &= "'" & outfordocno.Text & "',"
            sql &= "1)"
            sql &= " Update stock"
            sql &= " Set stqty=stqty-'" & stout.Text & "',"
            sql &= " stqty2=stqty2-'" & stout.Text & "'"
            sql &= " Where (stcode='" & Stname.SelectedValue & "')"
            sql &= " Update stdetail"
            sql &= " Set stbal='" & stqty.Text - stout.Text & "'"
            sql &= " Where (stcode='" & Stname.SelectedValue & "')"
            sql &= " And (stdate='" & outdate.Value.ToString("s") & "')"
        End If
        Try
            With comAdd
                .CommandType = CommandType.Text
                .CommandText = sql
                .Connection = mySQLConn
                .ExecuteNonQuery()
            End With

        Catch ex As Exception
            MessageBox.Show(ex.Message, "ข้อผิดพลาด", MessageBoxButtons.OK, MessageBoxIcon.Error)
            Exit Sub
        End Try
        MsgBox("บันทึกข้อมูลเรียบร้อยแล้ว")