Do I need to use classes?

Hi again folks,
As a relative newbie I am probably trying to run before I can walk but here
goes:

Thanks to all you good folks I have managed to get some sort of a site up and
running whereby people can view my catalogue, select items from it and then send
the aggregate amount to PayPal for payment processing. I have a precheckout page
where people can view their selected items before proceeding to the final
payment stage. My script is as follows:

$query = 'SELECT * FROM Catalogue WHERE id IN (' . implode( ',',
$_POST['selection'] ) . ')';
$result = mysql_query($query) or die ("Error in query: $query. " .
mysql_error());
$totalprice = 0;
echo "<table cellpadding=2 border=0>";

echo "<tr>";
echo "<td bgcolor='#FF8000' valign='top' align='center'><font face='Arial'
size='1'><u><b>Cat No</b></u></font></td>";
echo "<td bgcolor='#FF8000' valign='top' align='center'><font face='Arial'
size='1'><u><b>Description</b></u></font></td>";
echo "<td bgcolor='#FF8000' valign='top' align='center'><font face='Arial'
size='1'><u><b>Price</b></u></font></td>";
echo "</tr>";

while($row = mysql_fetch_row($result)) {
echo "<tr>";
echo "<td><font face='Arial' size='1'>" . $row[0] . "</font></td>";
echo "<td><font face='Arial' size='1'>" . $row[3] . "</font></td>";
echo "<td><font face='Arial' size='1'>£" . $row[6] . "</font></td>";
echo "</tr>";
$totalprice += $row[6];
}
echo "</table>";
echo "<p align='center'><b><font color='#FF0000'>Total price of selected items =
£$totalprice</br>Your credit card will be debited with this
amount</br></font></b></p>";
echo "<form action='https://www.paypal.com/cgi-bin/webscr' method='post'>
<input type='hidden' name='cmd' value='_xclick'>
<input type='hidden' name='business' value='myemailaddress'>
<input type='hidden' name='item_name' value='aggregatepurchase'>
<input type='hidden' name='currency_code' value='GBP'>
<input type='hidden' name='amount' value='$totalprice'>
<p align='center'><b>Payment method is via PayPal - The secure way to make
payments over the internet.</b></p>
<p align='center'><input type='image' src='x-click-but03.gif' name='submit'
alt='Make payments with PayPal - it's fast, free and secure!'></p>
</form>";

Yeah Yeah I know it needs tidying but it works.
My question is will it work in the real world. What happens if their are
multiple users all trying to checkout at the same time and trying to access the
same checkout script? Do I need to use classes?

Any help/suggestions greatly appreciated.

Regards
Dynamo

Dynamo wrote:
> Hi again folks,
> As a relative newbie I am probably trying to run before I can walk
but here
> goes:
>
> Thanks to all you good folks I have managed to get some sort of a
site up and
> running whereby people can view my catalogue, select items from it
and then send
> the aggregate amount to PayPal for payment processing. I have a
precheckout page
> where people can view their selected items before proceeding to the
final
> payment stage. My script is as follows:
>
> $query = 'SELECT * FROM Catalogue WHERE id IN (' . implode( ',',
> $_POST['selection'] ) . ')';
> $result = mysql_query($query) or die ("Error in query: $query. " .
> mysql_error());
> $totalprice = 0;
> echo "<table cellpadding=2 border=0>";
>
> echo "<tr>";
> echo "<td bgcolor='#FF8000' valign='top' align='center'><font
face='Arial'
> size='1'><u><b>Cat No</b></u></font></td>";
> echo "<td bgcolor='#FF8000' valign='top' align='center'><font
face='Arial'
> size='1'><u><b>Description</b></u></font></td>";
> echo "<td bgcolor='#FF8000' valign='top' align='center'><font
face='Arial'
> size='1'><u><b>Price</b></u></font></td>";
> echo "</tr>";
>
> while($row = mysql_fetch_row($result)) {
> echo "<tr>";
> echo "<td><font face='Arial' size='1'>" . $row[0] .
"</font></td>";
> echo "<td><font face='Arial' size='1'>" . $row[3] .
"</font></td>";
> echo "<td><font face='Arial' size='1'>£" . $row[6] .
"</font></td>";
> echo "</tr>";
> $totalprice += $row[6];
> }
> echo "</table>";
> echo "<p align='center'><b><font color='#FF0000'>Total price of
selected items =
> £$totalprice</br>Your credit card will be debited with this
> amount</br></font></b></p>";
> echo "<form action='https://www.paypal.com/cgi-bin/webscr'
method='post'>
> <input type='hidden' name='cmd' value='_xclick'>
> <input type='hidden' name='business'
value='myemailaddress'>
> <input type='hidden' name='item_name'
value='aggregatepurchase'>
> <input type='hidden' name='currency_code' value='GBP'>
> <input type='hidden' name='amount' value='$totalprice'>
> <p align='center'><b>Payment method is via PayPal - The secure way to
make
> payments over the internet.</b></p>
> <p align='center'><input type='image' src='x-click-but03.gif'
name='submit'
> alt='Make payments with PayPal - it's fast, free and secure!'></p>
> </form>";
>
> Yeah Yeah I know it needs tidying but it works.
> My question is will it work in the real world. What happens if their
are
> multiple users all trying to checkout at the same time and trying to
access the
> same checkout script? Do I need to use classes?
>
> Any help/suggestions greatly appreciated.
>
> Regards
> Dynamo

It does not look like you need to use a class, although it may make
things neater and nicer to deal with. There shoulden't be a PHP problem
if you have a mass of requests to the page so long as the SQL server
and web server are functioning properly and can handle the number of
requests.