PHP - What To Do ??? Prepared Sql Stament And Dynamic Query Becoming Impossible.

I'm trying to use a prepared statement inside a function and it's giving me some trouble. I have an RPG game I'm working on an want a function to include on pages that tells a user to collect their egg from the professor if they haven't already received it yet. When I try to call the function on the page these are the errors I get:

Notice: Undefined variable: link in /home/evoarena/public_html/Dev/functions.php on line 23

Fatal error: Uncaught Error: Call to a member function prepare() on null in /home/evoarena/public_html/Dev/functions.php:23 Stack trace: #0 /home/evoarena/public_html/Dev/login.php(59): egg_received() #1 {main} thrown in /home/evoarena/public_html/Dev/functions.php on line 23

$link is defined in a db config file and on the page I'm trying to call the function I have the files required like this so I'm wondering why it still thinks link is an undefined variable 

require "config.php";
require "functions.php";

Function Code:

function egg_received () {

  if (isset($_SESSION['username'])) {
     
    $username = $_SESSION['username'];
    $query = "SELECT egg_received FROM users WHERE username=?";
    if ($stmt = $link->prepare($query)) {
    
    $stmt->bind_param("s", $username);
    $stmt->execute();
    $result = $stmt->get_result();
    
    $egg = $result->fetch_array();
    
    if ($egg['egg_received'] == '0') {
    
      echo "<div class='alert alert-primary' role='alert'>
      Oh well hello there! It appears the professor is looking for you today!<br><a href='../world/professor.php'>Visit the Professor</a>
      </div>";
      
      require "footer.php";
      exit;
      
    }

} else {
    
     $error = $link->errno . ' ' . $link->error;
    echo $error;
}
}
}

Hi !

I am trying to translate my mysqli count query that works perfectly into prepared statements.

Unfortunately, after playing around and using my knowledge of PS, I have come up with this script which fails to execute and returns a http 500 error.

I may have missed something very silly, I require some guidance on fixing the error.

<?php


$conn = mysqli_connect("xxxx", "xxxx", "xxxx", "xxx");

$sel_query = "SELECT 
    S1, B1
    COUNT(IF(S1 = ?, 1, NULL)) 'Accepted',
    COUNT(IF(S1 = ?, 1, NULL)) 'Rejected',
    COUNT(IF(S1 = ?, 1, NULL)) 'Under_Review' FROM Enrol";
    
    $stmt = $conn->prepare($sel_query); 
    
	$Accepted="Accepted";
	$Rejected="Rejected";
	$Under_Review="Under Review";

	
	$stmt->bind_param("sss",$Accepted, $Rejected, $Under_Review);
	$stmt->execute();
	$result = $stmt->get_result(); // get the mysqli result
	  
	if($result->num_rows === 0) exit('No records found!');
	while($row = $result->fetch_assoc()) {  ?>
  
   
<tr>
        
        <td><?php echo $row["Accepted"]; ?></td>
        <td><?php echo $row["Rejected"]; ?></td>
        <td><?php echo $row["Under_Review"]; ?></td>
</tr>




</table>