If Persona needs to check for authentication, then change the model in your config/auth.php file. No need to do any joins or anything.

• Table: Persona
• Columns: id_Persona, Name, Age, City, Phone, Email, etc.
• N°Rows: 1.000's, contacts, users, refered, etc.

• Table: Usuario
• Columns: id_Persona, password, remember_token
• N°Rows: 10's, just users

Condition: Persona.id_Persona = Usuario.id_Persona

Auth: Persona.Email = <username> || Usuario.Password = <password>

That explain better why I need a join, can't just merge tables, the framework should adapt to my needs, no my needs to the framework, I can't have hundreds of rows in <NULL> just because I had to merge the tables... hope you can understand.

Do you know another way, @thomastkim? thanks!

So, if I'm understanding this correctly, users (Usario) can actually have a password without an email?

No, as it must exist a "Person" row with the same ID so it can exist an "User" row with given ID.

FOREIGN KEY (`id_persona`) REFERENCES `persona` (`id_persona`))

Can't exist an "User" without "Person", which have the email. "Email" is Not Null.

Ahh, I see. So a Persona has one Usario, and a Usario belongs to a Persona.

Try this then.

 // Import this at the top
use Hash;

// Add this, wherever you do your login check

// The fields
$email = $request->email;
$password = $request->password;

// Get person and his/her relationship with usario
$user = Persona::with('usario')->where('email', $email)->first();

// check if user exists, and if so, check his password
// Then login using the usario id
if ($user && Hash::check($password, $user->usario->password)) {
    Auth::loginUsingId($user->usario->id);
}

@thomaskim, thanks you'r right. Thanks for your idea, with that in mind, I changed postLogin() but inside AuthController, so I can preserve the Throttles and Remember features, and the core still unchanged, here's the code if I can help to another one:

//------------------------------------
Auth\AuthController.php
//------------------------------------

    protected function postLogin(Request $request)
    {
        $this->validate($request, [
            $this->loginUsername() => 'required', 'password' => 'required',
        ]);

        // If the class is using the ThrottlesLogins trait, we can automatically throttle
        // the login attempts for this application. We'll key this by the username and
        // the IP address of the client making these requests into this application.
        $throttles = $this->isUsingThrottlesLoginsTrait();

        if ($throttles && $this->hasTooManyLoginAttempts($request)) {
            return $this->sendLockoutResponse($request);
        }

        $credentials = $this->getCredentials($request);
        
        //Here's the custom SQL, so you can retrieve a "user" and "pass" from anywhere in the DB
        $usuario = \DB::select('
                SELECT
                    persona.nombre,
                    usuario.password
                FROM
                    persona
                INNER JOIN
                    usuario ON persona.id_persona = usuario.id_persona
                WHERE
                    persona.email = ?
                LIMIT 1', array($credentials['email']));

        // Instead of:
        // if (Auth::attempt($credentials, $request->has('remember'))) {
        if ($usuario && Hash::check($credentials['password'], $usuario[0]->password)) {
            Auth::loginUsingId($usuario[0]->id_persona, $request->has('remember'));

            // Put any custom data you need for the user/session
            Session::put('nombre', $usuario[0]->nombre);

            return $this->handleUserWasAuthenticated($request, $throttles);
        }

        // If the login attempt was unsuccessful we will increment the number of attempts
        // to login and redirect the user back to the login form. Of course, when this
        // user surpasses their maximum number of attempts they will get locked out.
        if ($throttles) {
            $this->incrementLoginAttempts($request);
        }

        return redirect($this->loginPath())
            ->withInput($request->only($this->loginUsername(), 'remember'))
            ->withErrors([
                $this->loginUsername() => $this->getFailedLoginMessage(),
            ]);
    }