Signup during registration is not registering users to the database record?

<pre lang="PHP">// Back end using php.

<pre><?php
	
$showAlert = false;
$showError = false;
$exists=false;
	
if($_SERVER["REQUEST_METHOD"] == "POST") {
	
	// Include file which makes the
	// Database Connection.
	include 'db_config.php';
	
	$username = $_POST["username"];
	$password = $_POST["password"];
	$cpassword = $_POST["cpassword"];
			
	
	$sql = "Select * from signup where username='$username'";
	
	$result = mysqli_query($conn, $sql);
	
	$num = mysqli_num_rows($result);
	
	// This sql query is use to check if
	// the username is already present
	// or not in our Database
	if($num == 0) {
		if(($password == $cpassword) && $exists==false) {
	
			$hash = password_hash($password,
								PASSWORD_DEFAULT);
				
			// Password Hashing is used here.
			$sql = "INSERT INTO `signup` ( `username`,
				`password`, `date`) VALUES ('$username',
				'$hash', current_timestamp())";
	
			$result = mysqli_query($conn, $sql);
	
			if ($result) {
				$showAlert = true;
			}
		}
		else {
			$showError = "Passwords do not match";
		}	
	}// end if
	
if($num>0)
{
	$exists="Username not available";
}
	
}//end if
	
?>

<?php
    
    if($showAlert) {
    
        echo ' <div class="alert alert-success 
            alert-dismissible fade show" role="alert">
    
            Success! Your account is 
            now created and you can login. 
            <button type="button" class="close"
                data-dismiss="alert" aria-label="Close"> 
                <span aria-hidden="true">×</span> 
            </button> 
        </div> '; 
    }
    
    if($showError) {
    
        echo ' <div class="alert alert-danger 
            alert-dismissible fade show" role="alert"> 
        Error! '. $showError.'
    
       <button type="button" class="close" 
            data-dismiss="alert aria-label="Close">
            <span aria-hidden="true">×</span> 
       </button> 
     </div> '; 
   }
        
    if($exists) {
        echo ' <div class="alert alert-danger 
            alert-dismissible fade show" role="alert">
    
        Error! '. $exists.'
        <button type="button" class="close" 
            data-dismiss="alert" aria-label="Close"> 
            <span aria-hidden="true">×</span> 
        </button>
       </div> '; 
     }
   
?>

<div class="form-group relative mb-25 mb-sm-20">

    
</div>
<div class="form-group relative mb-20 mb-sm-20">

    ^__i class="fas fa-lock transform-v-center">
</div>
<div class="form-group relative mb-20 mb-sm-20">

    ^__i class="fas fa-lock transform-v-center">
</div>
<div class="form-group form-check pl-0">
    <div class="d-flex justify-content-between">
        <div class="custom-control custom-checkbox">

            Remember me
        </div>
    </div>
</div>
SIGNUP
<div class="signup-login text-center"></div>