MySQL query is not perfectly writing data in the phpMyAdmin database

I have been trying to fix a problem, but without success.

When I input data and submit in my signup form some columns in my database are not affected.

<?php
require('backend/db_con/DB_Connection.php');

$success = false;

if(isset($_POST['Register'])){
    $F_name = $_POST['first_name'];
    $L_name = $_POST['last_name']; 
    $email = $_POST['email'];
    $add = $_POST['Address'];
    $Country = $_POST['country'];
    $City = $_POST['city'];
    $Zip = $_POST['zip_code'];
    $tele = $_POST['telephone'];
    $password = $_POST['password'];
    $confirm = $_POST['confirm'];

    //validations

    if($F_name=="" || $L_name=="" || $email==""  || $password=="" || $confirm=="" || $Country=="" || $City="" || $Zip="" || $add=""){
        $errorMessege = "Please enter the required fields.";
    }
    else if(!filter_var($email, FILTER_VALIDATE_EMAIL)){
        $errorMessege = "Please enter a correct email address";
    }
    else if($tele!="" && !is_numeric($tele)){
        $errorMessege = "Please enter a correct telephone number";
    }
    else if($password != $confirm){
        $errorMessege = "Your password and the confirmation does not match. Please try again.";
    }
    else if(strlen($password) <5){
        $errorMessege = "Password must be atleast 6 characters"; 
     }

    if(!isset($errorMessege)){
        $password = hash("sha256", $password);

        $sql = "INSERT INTO clients( first_name , last_name , email , Address , country , city , zip_code , telephone , password)
        VALUES('".$F_name."', '".$L_name."', '".$email."',  '".$add."', '".$Country."', '".$City."', '".$Zip."', '".$tele."', '".$password."')";
        mysqli_query($con, $sql);

        if(mysqli_affected_rows($con) > 0){
            $success = true;
        }
        else{
            $errorMessege = "This E-mail has already registerd. Please use login page to login or try signup using a different E-mail";
        }
    }
}

?>