PHP MYSQL PDO SUM of columns


I'm new to php and I've searched for the past hour and read all the documentation I could find and nothing is helping. I have a table that has a bunch of rows of data. I'm trying to pick one column from the whole table and add them all together. Here is what I got. All this tells me is how many rows there are that match my query, not the total sum of column I want. Any help is appreciated.

$res1 = $db->prepare('SELECT sum(distance) FROM trip_logs WHERE user_id = '. $user_id .' AND status = "2"');
$sum_miles = 0;
while($row1 = $res1->fetch(PDO::FETCH_ASSOC)) {
$sum_miles += $row1['distance'];
echo $sum_miles;

Best Solution

You're only returning one row in this instance. Modify your summed column to have an alias:

SELECT SUM(distance) AS totDistance FROM trip_logs ....

Now you can can fetch the row -

$row = $res1->fetch(PDO::FETCH_ASSOC);
echo $row['totDistance'];

No need to loop.