/**
  * Run the migrations.
  *
  * @return void
  */
 public function up()
 {
     //get all users
     $users = User::all();
     // and update new field external_identifier with member id
     foreach ($users as $user) {
         $email = $user->external_id;
         $member = Member::where('Email', '=', $email)->first();
         if (!is_null($member)) {
             $user->external_identifier = $member->ID;
             $user->save();
         }
     }
 }