PHP已准备好的将数据插入除一个表以外的所有表中的语句（MySQL）

Question

I'm working on an inbox system. On the front end, it uses jQuery and Ajax so the page doesn't refresh. I've got that part handled. On the back end, there are 3 tables (for now) that get data inserted.

Here is a basic rundown of the relation structures:

conversations:
conversation_id int(11) primary key
conversation_subject varchar(128)

conversations_members:
conversation_id int(11)
user_id int(11)
conversation_last_view int(10)
conversation_deleted int(1)

conversations_messages:
message_id int(11) primary key
conversation_id int(11)
user_id int(11)
message_date timestamp
message_text text

There is an additional problem since the sender_id is always 0, but that will have to be for another question since it's off topic. The problem lies in the conversations_members table. Everything else gets entered into the conversations and conversations_messages tables. Here is the PHP. The issue is the very last SQL query at the bottom:

<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

include('../inc/connect.php');
if (!isset($_SESSION['username'])) {
    session_start();
}
$recipient_username = "";
$sender_id = "";
$a = 0;
$b = 0;
if(isset($_POST['subject'], $_POST['msg_body']) &&     !empty($_POST['subject']) && !empty($_POST['msg_body'])) {

//get ID of sender
$sender_id_query = "SELECT id FROM `users` WHERE username = ?";
$stmt = $connection->prepare($sender_id_query);
$stmt->bind_param('s', $_SESSION['username']);
$stmt->execute();
$result = mysqli_query($connection, $sender_id_query);
if($result) {
    while($row = mysqli_fetch_assoc($result)) {
        //$row['id'] = $sender_id;           //neither of these work
        $sender_id = $connection->insert_id; //Always zero
    }
}
$stmt->close();

//get username of recipient
$recipient_name_query = "SELECT * FROM `users`";
$result = mysqli_query($connection, $recipient_name_query);
if($result) {
    while($row = mysqli_fetch_assoc($result)) {
        $row['username'] = $recipient_username;
    }
}
//define post variables
$msg_subject = $_POST['subject'];
$msg_body = $_POST['msg_body'];
$subject = $connection->real_escape_string(htmlentities($msg_subject));
$body = $connection->real_escape_string(htmlentities($msg_body));
$conversation_id = mysqli_insert_id($connection);


//GET RECIPIENT ID
$sql = "SELECT id FROM `users` WHERE username=?";
$stmt = $connection->prepare($sql);
$stmt->bind_param('s', $recipient_username);
$result = mysqli_query($connection, $sql);
if ($result) {
    while ($row = mysqli_fetch_assoc($result)) {
        $recipient_id = $row['id'];
    }
}
$stmt->close();

//INSERT SUBJECT INTO CONVERSATIONS TABLE
$stmt = $connection->prepare("INSERT INTO `conversations` (conversation_subject) VALUES(?)");
$stmt->bind_param('s', $subject);
$stmt->execute();
$stmt->close();


//INSERT THE IDs AND TIMESTAMPS INTO MESSAGES TABLE
$stmt = $connection->prepare("INSERT INTO `conversations_messages` (conversation_id, user_id, message_date, message_text)
                              VALUES(?, ?, NOW(), ?)");
$stmt->bind_param('iis', $conversation_id, $sender_id, $body);
$stmt->execute();
$stmt->close();

/*
 THE FOLLOWING DATA DOES NOT GET INSERTED.....
*/
//INSERT IDs, LAST_VIEWED, AND DELETED INTO MEMBERS TABLE
$stmt = $connection->prepare("INSERT INTO `conversations_members` (conversation_id, user_id, conversation_last_view, conversation_deleted)
                              VALUES (?, ?, ?, ?)");
$stmt->bind_param('iiii', $conversation_id, $recipient_id, $a, $b);
$stmt->execute();
$stmt->close();
}

I get no errors, and I'm not seeing any typos. Where did I go wrong?

Answer 1

Thanks to the suggestion of additional error checking, it led me to discover what was happening. I completely removed the while loops, and gave each $stmt variable it's own name since I discovered another error after removing the while loops. Every statement after the first was returning a FALSE value since the previous statement wasn't closed. This code works. I get no errors, and it inserts everything into the database as required.

$recipient_username = $_GET['username'];
$username = $_SESSION['username'];
$a = 0;
$b = 0;


//get ID of sender
$sender_id_query = "SELECT id FROM `users` WHERE username = ?";
$stmt = $connection->prepare($sender_id_query);
$stmt->bind_param('s', $username);
$stmt->execute();
$stmt->bind_result($sender_id);
$val = $stmt->fetch()[$sender_id];
$stmt->close();

//define post variables
$msg_subject = $_POST['subject'];
$msg_body = $_POST['msg_body'];
$subject = $connection->real_escape_string(htmlentities($msg_subject));
$body = $connection->real_escape_string(htmlentities($msg_body));
$conversation_id = mysqli_insert_id($connection);

//GET RECIPIENT ID
$recipient_id_query = "SELECT id FROM `users` WHERE username=?";
$stmt2 = $connection->prepare($recipient_id_query);
$stmt2->bind_param('s', $recipient_username);
$stmt2->execute();
$stmt2->bind_result($recipient_id);
$val_2 = $stmt2->fetch()[$recipient_id];
$stmt2->close();

//INSERT SUBJECT INTO CONVERSATIONS TABLE
$stmt3 = $connection->prepare("INSERT INTO `conversations` (conversation_subject) VALUES(?)");
$stmt3->bind_param('s', $subject);
$stmt3->execute();
$stmt3->close();

//INSERT THE IDs AND TIMESTAMPS INTO MESSAGES TABLE
$stmt4 = $connection->prepare("INSERT INTO `conversations_messages` (conversation_id, user_id, message_date, message_text)
                              VALUES(?, ?, NOW(), ?)");
$stmt4->bind_param('iis', $conversation_id, $sender_id, $body);
$stmt4->execute();
$stmt4->close();


//INSERT IDs, LAST_VIEWED, AND DELETED INTO MEMBERS TABLE
$stmt5 = $connection->prepare("INSERT INTO `conversations_members` (conversation_id, user_id, conversation_last_view, conversation_deleted)
                              VALUES (?, ?, ?, ?)");
$q = $stmt5->bind_param('iiii', $conversation_id, $recipient_id, $a, $b);
$stmt5->execute();
$stmt5->close();