Insert Code Error

Question

Can anyone help me find the error in this code please?
There is a code below this that sends an email, and it all works fine, but the data isnt being posted into the database for some reason (This code).
<?php
$con= require_once('../../connections/djdirect.php');
$firstname = ($_POST['firstname']);
$lastname = ($_POST['lastname']);
$email = ($_POST['email']);
$mobilenumber = ($_POST['mobilenumber']);
$date = ($_POST['datepicker']);
$timestart = ($_POST['timestart']);
$timeend = ($_POST['timeend']);
$addressline1 = ($_POST['addressline1']);
$addressline2 = ($_POST['addressline2']);
$addresscity = ($_POST['addresscity']);
$addresscounty = ($_POST['addresscounty']);
$addresspostcode = ($_POST['addresspostcode']);
$package = ($_POST['package']);
$addons = ($_POST['addons']);
$comments = ($_POST['comments']);
$discountcode = ($_POST['discountcode']);
$sql = "INSERT INTO quote (firstname, lastname, email, mobile, date, timestart, timeend, addressline1, addressline2, addresscity, addresscounty, addresspostcode, package, addons, comments, discountcode) VALUES ('$firstname', '$lastname', '$email', '$mobilenumber', '$date', '$timestart', '$timeend', '$addressline1', '$addressline2', '$addresscity', '$addresscounty', '$addresspostcode', '$package', '$addons', '$comments', '$discountcode')";
mysqli_close($con);
?>
Here is an image of the table in the database:

Answer 1

You defined your INSERT query but are not actually sending it to the database. You need something like:
mysqli_query($sql);
I use PDO, not MySQLi, so I may not have gotten the script quite right, but you get the idea.