PDO SUM MYSQL table - php

Question

I am learning as i go and been picking up snippets of code as i go and been working on this for the past few days and now i have thrown the towel in to seek help.
I am trying to calculate the sum of 2 columns in my database using PDO.
here is my code
<?php
$host = "localhost";
$db_name = "dbname";
$username = "root";
$password = "root";
try {
$con = new PDO("mysql:host={$host};dbname={$db_name}", $username, $password);
}
// show error
catch(PDOException $exception){
echo "Connection error: " . $exception->getMessage();
}
$query = "SELECT SUM (fill_up) AS TotalFill,
SUM (mileage_covered) AS Totalmiles
FROM fuel_cost";
$row = $query->fetch(PDO::FETCH_ASSOC);
$total_fill = $row['TotalFill'];
$total_miles = $row['Totalmiles'];
$myanswer = $total_fill/$total_miles;
//display the answer
echo $myanswer
?>
I have also checked my database table and both columns are varchar(32)
the error I am getting is Call to a member function fetch() on a non-object
I have searched into this but not sure what's the issue with the above code
Thank You in advance

Answer 1

Try this code :-
<?php
$servername = "localhost";
$username = "root";
$password = "root";
$dbname = "dbname";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT SUM (fill_up) AS TotalFill,
SUM (mileage_covered) AS Totalmiles
FROM fuel_cost";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while ($row = $result->fetch_assoc()) {
$total_fill = $row['TotalFill'];
$total_miles = $row['Totalmiles'];
$myanswer = $total_fill / $total_miles;
//display the answer
echo $myanswer;
die;
}
} else {
echo "0 results";
}
$conn->close();
?>