Sum of while row - php

Question

I'm new to php and I'm stuck. I have a report that allows a supervisor to show the working hours of the operators. I can show all the hours from the db, but I can't make a sum of all the hours. I want to display one more row that shows the total hours. How can I do that?
<?php
if(isset($_SESSION['username'])) {
$username = $_SESSION['username'];
} else {
header('Location: index.php');
die();
}
include('connect.php');
#$oret_e_punes = $_POST['oret_e_punes'];
#$grupi = $_POST['grupi'];
#$data_e_inserimit = $_POST['data_e_inserimit'];
#$data_e_inserimit_2 = $_POST['data_e_inserimit_2'];
$sql = "select grup_name from grupi";
$result = mysqli_query($dbCon, $sql);
if(!$result) {
die("Error");
}
?>
//html form
<?php
if(isset($_POST['insert'])) {
$insert = "select * from ore where grupi='$grupi' and (data between '$data_e_inserimit' and '$data_e_inserimit_2' and ore !=0)";
$result_insert = mysqli_query($dbCon, $insert);
if(!$result_insert) {
die("Error");
}
echo "<table id='table'>
<tr id='main'>
<td>Operatori</td>
<td>Grupi</td>
<td>Oret e punes</td>
<td>Data</td>
</tr>";
while ($row = mysqli_fetch_assoc($result_insert)) {
$id = $row['id'];
echo "<tr id='sub'>
<td>".$row['usr']."</td>
<td>".$row['grupi']."</td>
<td>".$row['ore']."</td> ---->working hours
<td>".$row['data']."</td>
</tr>";
$id++;
}
echo "</table>";
$_SESSION['$id'] = #$id;
}
?>

Answer 1

have a variable for hours before loop starts. Add in it hour of each record. After loop will end you will have your total hours
echo "<table id='table'>
<tr id='main'>
<td>Operatori</td>
<td>Grupi</td>
<td>Oret e punes</td>
<td>Data</td>
</tr>";
$hours = 0;
while ($row = mysqli_fetch_assoc($result_insert)) {
$id = $row['id'];
echo "<tr id='sub'>
<td>".$row['usr']."</td>
<td>".$row['grupi']."</td>
<td>".$row['ore']."</td> ---->working hours
<td>".$row['data']."</td>
</tr>";
$hours += $row['ore'];
$id++;
}
echo "<tr><td colspan='4'>Total</td><td>$hours</td></tr>";
echo "</table>";