php - Laravel 外部数据库中的外键引用表？

Question

我是 Laravel 和一般数据库的新手。我正在编写一个用于学生评估的网络应用程序。我有一个现有的 MySQL 数据库，其中包含我需要的一切；但是，我正在使用 Laravel 的 auth 用户表并尝试添加一个引用 MySQL 数据库中的 Teacher 表的外键。我不断收到以下错误...

php artisan migrate:fresh

In Connection.php line 664:
SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table users add constraint users_teacher_id_foreign foreign key (teacher_id) references p4j.teacher (teacher_id))

In Connection.php line 458: SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint

我的代码如下...

config/database.php

'mysql' => [
    'driver' => 'mysql',
    'host' => env('DB_HOST', '127.0.0.1'),
    'port' => env('DP_PORT', '3306'),
    'database' => env('DB_DATABASE', 'p4j'),
    'username' => env('DB_USERNAME', 'root'),
    'password' => env('DP_PASSWORD', '**mypassword**'),
    'charset' => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix' => '',
],

database/migrations/2014_10_12_000000_create_users_table.php

public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name');
        $table->string('email')->unique();
        $table->string('password');
        $table->integer('teacher_id')->unsigned();
        $table->rememberToken();
        $table->timestamps();
    });

    Schema::table('users', function (Blueprint $table) {
          $table->foreign('teacher_id')->references('teacher_id')->on('p4j.teacher');
    });
}

app/User.php

protected $fillable = [
    'name', 'email', 'password', 'teacher_id'
];

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

Answer 1

您只需要确保外键的数据类型 (p4j.teacher.teacher_id) 对应于用户表中 teacher_id 列的相同数据类型。

我们需要查看 p4j.teacher 表的结构。