namespace App;
    use IlluminateSupportFacadesDB;

    use IlluminateDatabaseEloquentModel;

    class Occurrence extends Model {
       protected $table      = 'occurrences';
       protected $guarded    = [];
       protected $primaryKey = 'id_occurrence';

       public function owner(){

          return $this->belongsTo(User::class, 'id_user_fk', 'id_user');

       }

       public function department(){

          return $this->belongsTo(Department::class, 'id_department_fk', 'id_department');

       }
    }

$occurrence = new AppOccurrence;
    => AppOccurrence {#2938}
    >>> $occurrence->first()->owner;
    => AppUser {#2947
         id_user: 2,
         name: "Jiripoqueiro",
         email: "jiripoca_vaipiar@yahoo.com.br",
         dateofbirth: "1985-08-15",
         active: 1,
         created_at: "2019-06-03 12:05:50",
         updated_at: "2019-06-03 12:05:50",
       }

>>> $occurrence = new AppOccurrence;
    => AppOccurrence {#2970}
    >>> $occurrence->first()->owner;
    => null

namespace App;

    use IlluminateNotificationsNotifiable;
    use IlluminateFoundationAuthUser as Authenticatable;

    class User extends Authenticatable
    {
       //protected $guarded = [];
       protected $primaryKey = 'id_user';
       use Notifiable;


        /**
         * The attributes that are mass assignable.
         *
         * @var array
         */
        protected $fillable = [
            'name', 'email', 'password',
        ];

        /**
         * The attributes that should be hidden for arrays.
         *
         * @var array
         */
        protected $hidden = [
            'password'
        ];
    }