php - laravel:具有外键的播种机

在我的数据库中，我已经有了表，即：通知表、状态表，它们有多对多的关系，这就是为什么我有一个称为通知状态的透视表。我用迁徙创造了它们，用播种机播种，一切都很好。现在我意识到我需要一个与通知表有多对一关系的额外表（natification->has many->alertfrequency）。当我试图迁移它时，它确实允许我这样做。
这是我的通知表

<?php

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

class CreateNotificationsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('notifications', function (Blueprint $table) {
            $table->increments('id');
            $table->string('website_url');
            $table->string('email');
            $table->string('slack_channel');
            $table->string('check_frequency');
            $table->string('alert_frequency');
            $table->string('speed_frequency');
            $table->boolean('active');
            $table->timestamps();
        });
    }

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

警报频率表，我要添加的新表，

 <?php

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

    class CreateAlertFrequenciesTable extends Migration
    {
        /**
         * Run the migrations.
         *
         * @return void
         */
        public function up()
        {
            Schema::create('alertFrequencies', function (Blueprint $table) {
                $table->increments('id');
                $table->integer('notification_id');
                $table->foreign('notification_id')
                      ->references('id')->on('notifications')
                      ->onDelete('cascade');
                $table->timestamps();
            });
        }

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

当我试图添加时，我得到了以下约束

  [Illuminate\Database\QueryException]
  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table `alertFrequencies` add constraint `alertfrequencies_notification_id_foreign` foreign key (`notification_
  id`) references `notifications` (`id`) on delete cascade)

任何有想法或建议的人。我很感激所有的想法和建议。

最佳答案

首先要做的是添加unsigned()，因为id也是无符号的：

$table->integer('notification_id')->unsigned();

如果没有帮助，请分割密钥创建并添加外键约束：

Schema::create('alertFrequencies', function (Blueprint $table) {
    $table->increments('id');
    $table->integer('notification_id')->unsigned();
    $table->timestamps();
});

Schema::table('alertFrequencies', function (Blueprint $table) {
    $table->foreign('notification_id')->references('id')->on('notifications')->onDelete('cascade');
});

关于php - laravel:具有外键的播种机，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41632979/