Данные не заносятся в базу данных после использование символов ' и -

function checkInput($username,$name,$last_name,$password,$rpassword,$email,$gender,$month,$day,$year){
    $errors = array();
    $user = array();
    if((strlen(trim($name))<2) or (!preg_match("/^[a-zA-Z\'-]+$/",$name))){
        $errors[] = "First name is invalid!";
        unset($_POST['first_name']);
    }
    if((strlen(trim($last_name))<2) or (!preg_match("/^[a-zA-Z\'-]+$/",$last_name))){
        $errors[] = "Last is invalid!";
        unset($_POST['last_name']);
    }
    if((strlen(trim($username))<5 or (!preg_match("/^[a-zA-Z0-9\'-]+$/",$last_name))) ){
        $errors[] = "Username is invalid!";
        unset($_POST['username']);
    }
    if((strlen(trim($password))<5) or (strlen(trim($password))<5))
        $errors[] = "Password should contain more then 4 chars!";
    if((($password)===($rpassword))===false)
        $errors[] = "Password does not match the confirm password!";
    if(!preg_match("/^[a-zA-Z0-9_\-.]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-.]+$/",$email)){
        $errors[] = "Email is invalid!";
        unset($_POST['email']);
    }
    if(!checkIfExists($username,"username"))
            $errors[] = "Username is already exists";
    if(!checkIfExists($email,"email"))
            $errors[] = "Email is already exists";  
    if($month==="na" or $day==="na" or $year==="na"){
        $errors[] = "Fill date of birth!";
    }
    if(count($errors)>0){
        foreach($errors as $err){
            echo "<p class='error'>".$err."</p>";
        }
        return false;
    }
    else{
        global $sql;
        $user = array($username,$name,$last_name,hashPass($password),$email);
        foreach($user as $clear){
            $clear = mysqli_real_escape_string(sql,htmlentities(htmlspecialchars(strip_tags($clear))));
        }
        $dates = array($day,$month,$year);
        $birth = implode("-",$dates);
        $user[] = $gender;
        $user[] = $birth;
    }
    return addUser($user);
}

foreach($user as $clear){
            $clear = mysqli_real_escape_string(sql,htmlentities(htmlspecialchars(strip_tags($clear))));
        }