Hai provato questo:
...
echo '<td>' . $row['salary'] . '</td>';
echo '<td><a href="edit.php?id=' . $row['id'] . '">Edit</a></td>';
echo '<td><a href="delete.php?id=' . $row['id'] . '">Delete</a></td>';
echo '<td>' . $row['title']*$row['salary'] . '</td>';
echo "</tr>";
...
Per sommare il totale di tutte le righe in una colonna è necessario utilizzare una variabile che viene incrementata ogni volta che il ciclo while viene eseguito:
// Declare variable for the place where the value
// of all the elements of the column are stored
$Total_total=0;
// loop through results of database query, displaying them in the table
while($row = mysql_fetch_array( $result )) {
...
echo '<td>' . $row['title']*$row['salary'] . '</td>';
echo "</tr>";
//Increment the value of the Total_total variable
//by the salary value of one row till the while loop finishes
$Total_total=$Total_total+$row['title']*$row['salary'];
}
// After the while loop add one more row where the "total's" will be shown
echo "<tr>";
echo '<td>' . Id column totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . Totals . '</td>';
echo '<td>' . $Total_total . '</td>';
echo "</tr>";
// Do the same for all the other columns where a total count is needed.
// 1) Declare variable ("$Total_total=0;")
// 2) Increment it each time with itself and something you
// need the totals for when while loop goes through one time
// ("$Total_total=$Total_total+$row['salary'];")
// 3) Print out the results after the while loop
// ("echo '<td>' . $Total_total . '</td>';")
