PHP SQL inner Join bool(false) - php

Question

I am attempting to get a 'total weight' for items a character is carrying. I am doing this by selecting the quantity of items in the characteritem table and comparing the weight which is set in the item table and they are joined by the iid (item id) column
I have tried a lot of different methods to no avail so I have looked up join statements. The issue I have is why the $result would return bool(false) and then how I can get the weights to add up afterwards.
Here is the code I am working with currently:
$sql = "SELECT *
FROM `characteritem` WHERE `owner` = '$user'
INNER JOIN item ON characteritem.iid=item.iid";
$result = $db_conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while ($row = $result->fetch_assoc()) {
$iid = $row['characteritem.iid'];
$quantity = $row['characteritem.quantity'];
$itemweight = $row['item.itemweight'];
$itemtotal = $itemweight + $itemweight;
echo $itemtotal;
}
}
var_dump($result);
SQL is working fine now. I have got the weight and quantity and gotten the individual results. How would I get the values to add together for $itemtotal?
$sql = "SELECT *
FROM `characteritem`
INNER JOIN item ON characteritem.iid=item.iid
WHERE `owner` = '$user'";
$result = $db_conn->query($sql);
if ($result->num_rows > 0) {
while ($row = $result->fetch_assoc()) {
$iid = $row['characteritem.iid'];
$quantity = $row['quantity'];
$itemweight = $row['itemweight'];
$itemtotal = $itemweight * $quantity;
echo $itemtotal;
}
}

Answer 1

Your SQL sintax is wrong, try
$sql = "SELECT *
FROM `characteritem`
INNER JOIN item ON characteritem.iid=item.iid
WHERE `owner` = '$user'";

Answer 2

Try This
$sql = "SELECT *
FROM `characteritem`
INNER JOIN item ON characteritem.iid=item.iid" WHERE `owner` = '$user';
$result = $db_conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while ($row = $result->fetch_assoc()) {
$iid = $row['characteritem.iid'];
$quantity = $row['characteritem.quantity'];
$itemweight = $row['item.itemweight'];
$itemtotal = $itemweight + $itemweight;
echo $itemtotal;
}
}
var_dump($result);