insert images in another table with foreign key - php

Question

I have two tables in my db, telephones(id, title, price) and images(id, tp_id, photos) I went in the images table and put a foreign key on the tp_id column to match the id in the telephones table so that every image is linked to a telephone. But the problem is my images go into the table fine but the tp_id column always has the value of 0, what I am missing here? can somebody guide me? Thanks
PS: I know about the security vulnerability of my code I am just doing some test here!
<?php
if (isset($_POST['submit'])) {
include 'dbconnect.php';
for ($i = 0; $i < count($_FILES["photo"]["name"]); $i++) {
$target = "img/"; //This is the directory where images will be saved
$target_files = $target . basename($_FILES['photo']['name'][$i]); //This gets all the other information from the form
$ad_title = $_POST['title'];
$ad_price = $_POST['price'];
$ad_photo = $target . ($_FILES['photo']['name'][$i]);
if (!move_uploaded_file($_FILES['photo']['tmp_name'][$i], $target_files)) { //Tells you if its all ok
echo "Sorry, there was a problem uploading your file.";
} else { //Gives and error if its not
$sql = "INSERT INTO telephones (title, price) VALUES ('$ad_title', '$ad_price')";
$conn->query($sql);
$sql1 = "INSERT INTO images (photos) VALUES ('$ad_photo') ";
$conn->query($sql1);
//Writes the photo to the server
header('location: addconfirm.php');
}
}
}
?>

Answer 1

get the last inserted primary key value using this
$last_id = $conn->insert_id;

Answer 2

You need to get last insert id form telephones table using $conn->insert_id; and the insert into images table as
$sql = "INSERT INTO telephones (title, price) VALUES ('$ad_title', '$ad_price')";
$conn->query($sql);
$tp_id=$conn->insert_id;// get last insert id
$sql1 = "INSERT INTO images (photos,tp_id) VALUES ('$ad_photo',$tp_id) ";
$conn->query($sql1);
Note:- Your script is Open for sql injection check How can I prevent SQL injection in PHP? to prevent it

Answer 3

Question has already been answered many times Use : MySQL: LAST_INSERT_ID()
$sql = "INSERT INTO telephones (title, price) VALUES ('$ad_title', '$ad_price')";
$conn->query($sql);
$tp_last_insert_id = $conn->LAST_INSERT_ID;// get last insert id
you should call this function right after you insert to get the latest added id
$sql1 = "INSERT INTO images (photos,tp_id) VALUES ('$ad_photo',$tp_last_insert_id) ";
$conn->query($sql1);