if the database is empty, code will not work - database

Question

if the database does not contain an entry, the code will not work. If an entry exists, the code works. Does anyone know why the code only works if there is already an entry in the database?
I get the timeout error:
Maximum execution time of 30 seconds exceeded
_
with the code I create the user, then his profile in connection with the inviting URL. A unique code with a length of 7 characters is created, which is the individual invitation URL.
I need the loop because it has to be checked if the code has ever been generated. Or is there a better solution?
protected function create(array $data)
{
if($data['gender'])
{
$avatar = 'defaults\avatars\male.jpg';
}
else
{
$avatar = 'defaults\avatars\female.jpg';
}
if (array_key_exists('team_id', $data) && $data['team_id']){
$team = $data['team_id'];
}else{
$team = Null;
}
if (isset($data['invited_id']) && $data['invited_id']){
$invited_from = $data['invited_id'];
}else{
$invited_from = Null;
}
$user = User::create([
'name' => $data['name'],
'team_id' => $team,
'invited_from_id' => $invited_from,
'username' => $data['username'],
'email' => $data['email'],
'password' => bcrypt($data['password']),
'birthday' => $data['birthday'],
'gender' => $data['gender'],
'slug' => str_slug($data['username']),
'avatar' => $avatar,
'active' => false,
'activation_token' => str_random(255)
]);
$user->profile()->save(new Profile());
while (true) {
$randomstring = substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyz"), 0, 7);
if (Invite::where('url','!=', $randomstring)->exists()) {
Invite::create([
'user_id' => $user->id,
'url' => $randomstring
]);
break;
}
}
//store notify for user in database
$usern = User::find($invited_from);
if($usern) {
User::find($usern->id)->notify(new NotifyInvite($user));
}
return $user;
}

Answer 1

The problem is not with your database, the problem is that you never break out of your loop if the condition is not satisfied. So while(true) will run forever. You need to add a default case to your condition, which will exit the loop.