How to accept a PostgreSQL database quantity in a php script? - php

Question

This is the simple snippet of code that I'm trying to edit for a school project. The problem as far as I can understand, is that its fetching the quantity right but it may not be getting stored in the variable $quantity. I've tried debugging it to no success. Also, The simple addition is giving bizarre results.
Please help. The code is as follows
<?php
include("DB.php");
$id = $_POST["flower_id"];
$add_quantity = $_POST["quantity"];
echo "FlowerID";
echo $id;
echo "<br>";
echo "Add Quantity";
echo $add_quantity;
echo "<br>";
$con = pg_connect("host=localhost dbname=kruttika user=kruttika");
$quantity = pg_query("select quantity from inventory where flower_id='$id'");
$new = $quantity;
echo "Fetched Quantity";
echo $new;
echo "<br>";
if(!$con)
echo "Error<br>";
else
{
$new_quantity = $new + $add_quantity;
echo "Total Quantity";
echo $new_quantity;
echo "<br>";
$sql = "update inventory set quantity=$new_quantity where flower_id='$id'";
echo "SQL injected";
echo $sql;
echo "<br>";
$result=pg_query($sql);
}
echo $result;
echo "<br>";
//echo "<script>location.href=\"adminindex.html\"</script>";
?>

Answer 1

I think the problem is:
$quantity = pg_query("select quantity from inventory where flower_id='$id'");
pg_query() doesn't return the actual value, it returns a pg_fetch_result().
You must fetch the result to get the desidered value. See the examples on the documentation linked above.