PHP - Can Anyone Identify What I Am Doing Wrong? Can't Display Results..

$default_apps = mysql_query("SELECT * FROM apps WHERE `default`='1'") or die(mysql_error());
$user_apps = mysql_query("SELECT * FROM user_apps WHERE `user_id`='$user_id'") or die(mysql_error());
while($row = mysql_fetch_array($default_apps))
{
$url = $row['download_url'];
$name = $row['name'];
   echo $row['name'];
   echo "<a href='$url'>$name</a><br />";
} 
while($raw = mysql_fetch_array($user_apps)){
$app_id = $raw['app_id'];
}
$select_user_apps = mysql_query("SELECT * FROM apps WHERE `app_id`='$app_id' ");
while($rop = mysql_fetch_array($select_user_apps))
{
$name = $rop['name'];
$url = $rop['download_url'];
echo $name;
echo $url;
}

Folks,

I managed to get this piece of code working.

But I need you to check if it is buggy or in error or not.

I will add VALIDATION later. Just let me know is this how you query db with mysqli_stmt_bind_result (prepared statement using procedural style) and display results on screen ?

Don't worry about pagination. i will add that later. Just let me know if I got the basics correct or not to display results from db or not. That is all.

Note my comments in CAPITALS. They are questions to which I need answers.

conn.php

	<?php
	$db_server = 'localhost';
$db_user = 'root';
$db_password = '';
$db_database = 'test';
	$conn = mysqli_connect("$db_server","$db_user","","$db_database");
	//SHOULD I KEEP FOLLOWING 1 LINE INTACT HERE OR DUMP IT TO main file search.php ?
$conn->set_charset('utf8mb4');//Always use Charset.
//HOW TO CONVERT ABOVE LINE TPO PROCEDURAL ?
	if (!$conn)
{
    //HOW TO WRITE CODE SO FOLLOWING TECHNICAL ERROR IS WRITTEN TO ERROR FILE AND NOT SHOWN TO USER ?
    //Error Message to show user in technical/development mode to see errors.
    die("Database Error : " . mysqli_error($conn));
	    //Error Message to show User in Layman's mode to see errors.
    die("Database error.");
    exit();
}
	?>
	

Q1. Do not forget to answer my question you see in CAPITALS in above code (conn.php).

Check the search.php before replying.

error_reporting.php

	<?php
ini_set('error_reporting','E_ALL');
ini_set('display_errors','1');
ini_set('display_startup_errors','1');
error_reporting(E_ALL);
	//SHOULD I KEEP FOLLOWING 1 LINE INTACT HERE OR DUMP IT TO main file search.php ?
mysqli_report(MYSQLI_REPORT_ERROR|MYSQLI_REPORT_STRICT);
?>
	

Q2. Do not forget to answer my question you see in CAPITALS in above code (error_reporting.php).

Check the search.php before replying.

search.php

	<?php
//include('error_reporting.php');
error_reporting(E_ALL);
ini_set('error_reporting',E_ALL);
ini_set('display_errors','1');
ini_set('display_startup_errors','1');
?>
	<form name = "search" method = "POST" action="">
<label for="keywords">Keywords:*</label>
<input type="text" name="keywords" id="keywords" placeholder="Input Keywords" required>
<br>
<button type="submit">Submit</button><br>
<button type="submit" value="submit">Submit</button><br>
<input type="submit" value="submit"><br>
<button name=submit value=" ">Search</button><br>
<button type="submit" name="submit" value="submit">Search</button>
<br>
<input type="reset">
<br>
</form>
	<?php
	if($_SERVER['REQUEST_METHOD'] === 'POST')
{
    if(ISSET($_POST['submit']))
    {
        if(ISSET($_POST['keywords']))
        {
            $keywords = $_POST['keywords'];
        }        
        
        //SHOULD I KEEP FOLLOWING 1 LINE INTACT HERE OR DUMP IT TO error_reporting.php ?
        mysqli_report(MYSQLI_REPORT_ERROR|MYSQLI_REPORT_STRICT);        
        
        //SHOULD I KEEP FOLLOWING 5 LINES INTACT HERE OR DUMP IT TO conn.php ?
        $conn = mysqli_connect("localhost","root","","test");
        $conn->set_charset("utf8mb4");
        if(mysqli_connect_error())
        {
            echo "Could not connect!" . mysqli_connect_error();
        }
	        $query = "SELECT page_url,link_anchor_text,page_description,keyphrases,keywords FROM links WHERE keywords = ?";
	        $stmt = mysqli_stmt_init($conn);
	        //FIRST ATTEMPT TO DISPLAY TBL RESULTS USING mysqli_stmt_bind_result() FUNCTION. TEST RESULT: ATTEMPT A FAILURE!
        if(mysqli_stmt_prepare($stmt,$query))
        {
            mysqli_stmt_bind_param($stmt,'s',$keywords);
	            $stmt_execution = mysqli_stmt_execute($stmt);
            if($stmt_execution === FALSE)
            {
                printf("Error: %s.\n", mysqli_stmt_error($stmt));
                printf("Error: %d.\n", mysqli_stmt_errno($stmt));
                die;
            }
            
            $bind_result = mysqli_stmt_bind_result($stmt,$page_url,$link_anchor_text,$page_description,$keyphrase,$keywords);
            if($bind_result === FALSE)
            {
                printf("Error: %s.\n", mysqli_stmt_error($stmt));
                printf("Error: %d.\n", mysqli_stmt_errno($stmt));
                die;
            }
            
            $stmt_fetch = mysqli_stmt_fetch($stmt);
            if($stmt_fetch === FALSE)
            {
                printf("Error: %s.\n", mysqli_stmt_error($stmt));
                printf("Error: %d.\n", mysqli_stmt_errno($stmt));
                die;
            }
            
            while(mysqli_stmt_fetch($stmt))
            {
                echo "$page_url"; echo "<br>";
                echo "$link_anchor_text"; echo "<br>";
                echo "$page_description"; echo "<br>";
                echo "$keyphrase"; echo "<br>";
                echo "$keywords"; echo "<br>";
                echo "|";
                echo "<br>";
            }
            
            mysqli_stmt_close($stmt);
            mysqli_close($conn);
        }
        else
        {
            die("QUERY failed!)";
        }
	

Q3. Anything I should know ?