mysql comparing two integers from two tables - php

Question

if($num>0) {
echo "<table border=2> Table Request".$_SESSION['s1'];
echo"<tr>
<td>Id</td><td>Drug</td><td>Quantity</td>
</tr>";
for($i=0;$i<$num;$i++) {
$row=mysql_fetch_row($result);
$r[$i]=$row[1];
echo "<tr>";
for($j=0;$j<$num1;$j++) {
echo"<td>$row[$j]</td>";
}
echo"<td><input type='Checkbox' name='p[$i]' value='on' unchecked /></td>";
echo"<td><input type='txt' name='q[$i]' /></td>";
echo"</tr>";
$r[$i]=$row[1];
}
if(isset($_POST['p'])) {
foreach($_POST['p'] as $key=>$value) {
if($value == "on") {
$query8 = "select $r[$i] from $_SESSION['t'] ";
echo $query8;
$result8 = mysql_query($query8);
$num8=Mysql_num_rows($result8);
if($num8!=0) {
$query7="select qun from $_SESSION['t']";
$result7 = mysql_query($query8);
//?????????????????
}
}
echo"</table>";
}
}//result
}//else
I have a table request and another table for example E.
I want to compare the field quantity of these tables
if(select qun from request)<((select qun from $_SESSION['t'])) // some work
How can I write this code in the part that I marked with many question marks?
is this correct?

Answer 1

If you really want what the title says, why you don't do something like that
SELECT table1.quantity AS qu1, table2.quantity AS qu2 FROM table1, table2 WHERE your_conditions;
When you get the results, you can compare qu1 against qu2.
But if you are looking for something different, than please be more specific with your question.
Actual example:
$query8 = 'SELECT '.$_SESSION[ 't'].'.'.$r[$i].' AS qu1, request.qun AS qu2 FROM '.$_SESSION[ 't'].', request';
$result8 = mysql_query($query8);
while ($row8 = mysql_fetch_array($result8)) {
if ($row8[ 'qu1'] < $row8[ 'qu2']) {
echo 'the value from '.$r[$i]. ' is smaller';
} elseif ($row8[ 'qu1'] > $row8[ 'qu2']) {
echo 'the value from '.$r[$i]. ' is bigger';
} else {
echo 'both values are same';
}
}