shopping cart - in the need of guidance

[Anon]

I was wondering if anyone can teach me the proper way to calculate total cost of the products, which have been placed into the cart by a shopper.

I have already made a script that inserts the user picked product data and user id into mysql table. I have already made a catalog so there is no worry there.

Basically all i wanna learn is how to require mysql'i with the user id, place the items' data into a html table, from there you can modify the quantity, has recalculate button or just remove.

If anyone knows the drill, please help

If i forget to thank you afterwards, I'll say it now, thanks

[Anon]

PHP can do all kinds of math functions. You'll discover many simply by experimenting.

You might have something like:
$quantity = 7;
$price = 14;
echo "$quantity";
echo "green widgets at ";
echo "$price ";
echo "apiece ";
echo "equals ";
$total = ($quantity * $price);
print $total;
?>

[Anon]

Or, save a step:

<?php
$quantity = 7;
$price = 14;
echo "$quantity green widgets at $price apiece equals " . ($quantity * $price) . " ";
?>

[Anon]

ok this part of the code is understandable but what if i'd like to change the quantity in html and it automaticly changes the total cost. I thought it must be somekind of a submit button that refreshes the page or stmh. Anyway this is my code so far:

$select = "SELECT * FROM bertool where code=$productd";
$result = mysql_query($select)
or die("Päring ebaõnnestus");
//siin ma ei tea, mis on sinu tabeli väljade nimed 🙁
while ($row = mysql_fetch_row($result)) {
$CO=$row[0];
$NA=$row[1];
$PR=$row[3];
print "<table>\n";

print "\t<tr>\n";

echo "\t\t<td width=\"250\" height=\"14\" ><div align=\"left\"><font size=\"3\">$NA</font>&nbsp;</div></td>\n";
print "\t\t<td width=\"250\" height=\"14\" ><input type=\"text\" size=\"3\" name=\"qty[]\" value=\"$qty\"></td>\n";
if (empty($qty)) {
$qty = 1;

}
print "\t\t<td width=\"50\" height=\"14\"><div align=\"right\"><font size=\"3\">$HI</font>&nbsp;</div></td>\n";
}
$TOTAL=($PR*$qty);
print "\t</tr>\n" ;

    }
}

print "\t<tr>\n";
mysql_close();
echo "\t\t<td width=\"250\" height=\"16\" ><div align=\"left\"><font size=\"3\">It will cost you:</font>&nbsp;</div></td>\n";
print "\t\t<td width=\"50\" height=\"14\"><div align=\"right\"><font size=\"3\"><b>$total</b></font>&nbsp;</div></td>\n";

"</table>\n";

But i'd like to add somewhere in the code that, when you change the quantity in the input box, then when pushing change or recalculate, it automaticly changes the value total.
Maybe its better with javascript or smth