skip stmt block - php

Question

I am brand new to php and I ran into a problem that has already taken a few hours of poking around and researching and I could not find anything like it anywhere around the net.
Database:MyPHPAdmin winserver
Goal: Create a new row in table 'photo'. Take the last insert p_id for the current user and update the table accessible_to by creating a new row with that p_id.
I know I can create a trigger, and no it does not work either don't know why. Run out of ideas how.
What I found out by simply printing before-in-after the if statement
if ($stmt = $mysqli->prepare("insert into accessible_to values(?, ?, ?)"))
is that it just bypasses it.
Please post your suggestions.
P.S. The if statement above to which I am referring has been twisted in several ways and yet it does not work.
The connection is already imported.
Thank you a lot.
if(!isset($_SESSION["id"])) {
echo "You are not logged in. ";
echo "You will be returned to the homepage in 3 seconds or click here.\n";
header("refresh: 3; index.php");
}
else {
//if the user have uploaded a photo, insert it into database
if(isset($_POST["ext"])) {
//insert into database, note that p_id is auto_increment
if ($stmt = $mysqli->prepare("insert into photo (ext, owner_id) values (?,?)")) {
$stmt->bind_param("ss", $_POST["ext"], $_SESSION["id"]);
$stmt->execute();
$stmt->close();
$id = htmlspecialchars($_SESSION["id"]);
}
//The following function is fetching the last added p_id in PHOTO by the user with the current SESSION
//Do not simply get the last p_id in PHOTO because someone else might have just added another picture meanwhile
if ($stmt = $mysqli->prepare("select MAX(p_id) from photo where owner_id = ?")){
$stmt->bind_param("s", $id);
$stmt->execute();
$stmt->bind_result($p_id);
if ($stmt->fetch()){
$p_id = htmlspecialchars($p_id);
}
}
echo "BEFORE accessible_to insertion";
echo '<br />';
if ($stmt = $mysqli->prepare("insert into accessible_to values(?, ?, ?)")){
echo "Finally inside accessible_to insertion";
echo '<br />';
$stmt->bind_param("iss", $p_id, $id, 'T');
$stmt->execute();
$stmt->close();
}
echo "AFTER accessible_to insertion";
echo '<br />';
}
//if not then display the form for posting message
else {
echo "Something";

Answer 1

You can't boolean test an assignment and expect it to return a different result. What you want to test for is if $stmt->execute successfully executed or not.
$stmt = $mysql->prepare("insert into foo values (?,?)");
$stmt->bind_param(1,$f1);
$stmt->bind_param(2,$f2);
if ($stmt->execute()) {
... worked
} else {
... fubar
}

Answer 2

You have to start by calling mysqli::connect($server, $user, $pw, $db). The best way to do that is by constructing an object like:
$connection = new mysqli($server, $user, $password, $db);
if ($connection->errno)
{
echo "Connection failed";
echo $this->connection->error;
}
else
{
$stmt = $connection->prepare("insert into photo (ext, owner_id) values (?,?)")) {
$stmt->bind_param("ss", $_POST["ext"], $_SESSION["id"]);
$stmt->execute();
$stmt->close();
}