file_get_contents() not working with require_once() in php

Question

I am trying to initialize a database once my index.php file gets open in browser for the first time.

I had first deploy.php that had an html code to specifically on submit it sends $_POST information to initialize. "it was working just fine".

Then I thought of better solution require_once(deploy.php) at the top of my index.php file, and now my file_get_contents() not returning the query into the variables and receiving an error that

General error: trying to execute an empty query

My code in deploy.php:

try {

        $USER_TABLE_QUERY = file_get_contents("./usertable.sql");
        
        $conn = new PDO($DB_DSN, $DB_USER, $DB_PASSWORD);
        
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        $conn->exec("$_USER_TABLE_QUERY");

} catch(PDOException $error) {
        
        echo $USER_TABLE_QUERY . "<br>" . $error->getMessage();
}

contents of usertable.sql :

CREATE TABLE IF NOT EXISTS `user` (
  user_id INT(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(150) NOT NULL,
  fullname VARCHAR(150) NOT NULL,
  email VARCHAR(150) NOT NULL,
  `password` VARCHAR(150) NOT NULL,
  `date` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
  )

EDIT NOTE:

I have even created a very simply php code:

<?php

$_sql = file_get_contents("hello.txt");

echo "this is sql:".$sql;

?>

and the content of hello.txt:

hello world

I have moved all the files to be in the same directory with each other but yet file_get_contents() not returning anything

is it somehow require_once() not executing file_get_contents() function?

Answer 1

I got it fixed by:

Adding all the code that was inside deploy.php inside index.php and now file_get_contents() working just fine, even though I still don't understand why deploy.php wasn't able to use file_get_contents() inside of it. And I hope if someone willing to still provide more clear answer about this! Thanks :)