PHP: Function no query & return - php

Question

I hope that someone sharp on PHP can help me with problem, that i really don't understand.
I have 2 scripts. 1: test.php 2:functions.php.
I created a little test where i called a functions in functions.php frim test.php and it work fine. I got a return and it was as expected. I also have a third script register.php where i have a query to a database and that work fine.
So I wanted the query to work as a function written in functions.php
Problem: It seems that it won't make the database query! But there is createt a connection
If I move the exactly same query to test.php, it works! Is there some kind of speciel reason for this? I quit new to php, but knows a little about Java, C, JavaScript, Python.
I have checked that my include / require is all in order.
1: test.php:
<?php
require 'includes/functions.php';
$name = 'testuser';
$_ok = 0;
$_ok = check_username ($name);
printf ( 'Navn i database?: ' . $_ok . '<br>' );
?>
2: functions.php:
<?php
require 'includes/db_connect.php';
// Check connection
if (! $mysqli) {
die ( 'mysqli_init_failed' );
}
if (mysqli_connect_errno ()) {
die ( 'Failed to connect to the Database, Sorry..! errorcode: ' .
mysqli_connect_errno() . ' <br>' . 'Error Type: ' . mysqli_connect_error () );
}
if ($debug_mode_c) {
print ('Connection Established: ' . mysqli_get_host_info ( $mysqli ) . '<br>') ;
print ('session_id: ' . session_id ()) . '<br>';
}
// Set HTML-Header to utf-8.
header ( 'Content Type: text/html; charset=UTF-8' );
// Functions
function check_username($_ok) {
$name = 'testuser';
$prep_stmt = "SELECT username FROM customs WHERE username=? LIMIT 1 ";
$stmt = mysqli_prepare($mysqli, $prep_stmt);
mysqli_stmt_bind_param($stmt, 's', $name);
mysqli_stmt_execute($stmt);
mysqli_stmt_bind_result($stmt, $name_db);
mysqli_stmt_fetch($stmt);
if ($name == $name_db) {
echo "hello";
mysqli_close ($stmt);
$_ok = 0;
} else {
$name = '';
$_ok = 2;
}
mysqli_free_result($stmt);
mysqli_close($stmt);
return $_ok;
}

Answer 1

Maybe found the reason for no query.
Apparently the include script containing establish connection, is not loaded as the function is called in functions.php.
When the query code is in test.php, that include functions.php, all code is read, also the connection for the database.
But even if include 'db_connect' is inside function, it won't work !?! :-(

Answer 2

There is nothing like noquery() function in PHP. please just check it in the include file of the database connection. you will find a user defined function in your include file of the database connection.