How to write to mysql database?

Question

I used localhost and everything works fine, however, when I hosted it in digital ocean, certain POST functions don't write to the mysql database.

I've tried using Postman to test the code, and it returns 200 OK and error writing to database.

My db_functions code:

 public function insertNewListing($name,$imgPath,$price,$listingId,$descriptions,$packageOne,$packageTwo,$moreDescriptions,$itinerary,$imgPathTwo,$imgPathThree)
{
    $stmt= $this->conn->prepare("INSERT INTO `Longhouses`(`Name`, `Link`,`Price`,`ListingId`,`descriptions`,`PackageOne`,`PackageTwo`,`MoreDescription`,`Itinerary`,`ImageTwo`,`ImageThree`) VALUES (?,?,?,?,?,?,?,?,?,?,?)") or die ($this->conn->error);

    $stmt->bind_param("sssssssssss",$name,$imgPath,$price,$listingId,$descriptions,$packageOne,$packageTwo,$moreDescriptions,$itinerary,$imgPathTwo,$imgPathThree);
    $result = $stmt->execute();
    $stmt->close();

    if($result)
        return true;
    else
        return false;
}

My add_listing function:

<?php
require_once '../../db_functions.php';
$db = new DB_Functions();

if(isset($_POST['name'])&&isset($_POST['imgPath'])&&isset($_POST['price'])&&isset($_POST['listingId'])&&isset($_POST['descriptions'])&&isset($_POST['packageOne'])&& isset($_POST['packageTwo'])&&isset($_POST['moreDescriptions'])&& isset($_POST['itinerary'])&& isset($_POST['imgPathTwo'])&& isset($_POST['imgPathThree']))
{
$name = $_POST['name'];
$imgPath = $_POST['imgPath'];
$price = $_POST['price'];
$listingId = $_POST['listingId'];
$descriptions = $_POST['descriptions'];
$packageOne = $_POST['packageOne'];
$packageTwo = $_POST['packageTwo'];
$moreDescriptions = $_POST['moreDescriptions'];
$itinerary = $_POST['itinerary'];
$imgPathTwo = $_POST['imgPathTwo'];
$imgPathThree = $_POST['imgPathThree'];


$result = $db->insertNewListing($name,$imgPath,$price,$listingId,$descriptions,$packageOne,$packageTwo,$moreDescriptions,$itinerary,$imgPathTwo,$imgPathThree);
if($result)
    echo json_encode("ADD LISTING SUCCESFUL");
else
    echo json_encode("error writing to database");

}