如何查找具有数量值的两列的总和

Question

Ok so I am a lil confused how to go about this and seek some help..

I have a mysql db that has a column named quantity and another called price_paid

what I want to do is take and add up the entire column of price_paid but to also take into account a quantity higher than 1.

Ex..

_____________     ______________   
|  quantity  |   | price_paid  | 
--------------   ---------------
       1              2.99 
       2              9.99
       1              1.99

How would I create the php / mysql to make that = a total of 24.96 ?

So far I am able to get the total of price_paid but what I have doesn't take into account the quantity column and it's value.

$comic_totals = "SELECT sum(price_paid) AS value_sum FROM `comic_db`.`comic_db`";
$total_db = mysqli_query($comic_connect, $comic_totals);
if(!total_db){
        echo "Failed";
}
$tot_array = mysqli_fetch_assoc($total_db);
$sum = $tot_array['value_sum'];
echo "$".$sum;

so how do I turn that into what I need? Thanks

Answer 1

Let MySQL take care of multiplying the price by the quantity...

SELECT SUM(quantity * price_paid) AS value_sum