Laravel 表：只能有一个自动列，并且必须定义为键

我已经使所有整数都无符号，但我仍然得到错误.我需要改变什么？

<?php

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateFacebook extends Migration {

    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
    Schema::create('facebook', function($table)
        {
        $table->increments('id');
        $table->integer('user_id')->unsigned();
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade')->onUpdate('cascade');
        $table->timestamps();
        $table->string('username', 255);
        $table->bigInteger('uid', 20)->unsigned();
        $table->string('access_token', 255);
        $table->string('access_token_secret', 255);
        $table->string('photoURL', 255);
        $table->string('profileURL', 255);
        $table->string('firstName', 255);
        $table->string('lastName', 255);
        $table->string('gender', 255);
        $table->string('age', 20);
        $table->integer('birthDay')->unsigned();
        $table->integer('birthMonth')->unsigned();
        $table->integer('birthYear')->unsigned();
        $table->string('email', 255);
        $table->string('phone', 30);
        $table->string('address', 255);
        $table->string('country', 100);
        $table->string('region', 100);
        $table->string('city', 100);
        $table->string('zip', 20);
        });
        }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('facebook');
    }

}

SQLSTATE[42000]: Syntax error or access violation: 1075 Incorrect table definition; there can be only one auto column and it must be de fined as a key

非常感谢.