在 Laravel 8 上限制遷移的外鍵出現語法錯誤

Question

我正在嘗試在 MySQL 8.0.21 - MySQL 社區服務器上執行一些 Laravel 8 Migrations，並嘗試使用一些外鍵關系，但遷移失敗

Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1")

我收到的第二個錯誤聲明是：

PDO::prepare("alter table `user_course` add constraint `user_course_user_id_foreign` foreign key (`user_id`) references `users` ()")

將在關系遷移中使用的第一個表是 users 表：

public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->string('email')->unique();
        $table->timestamp('email_verified_at')->nullable();
        $table->string('password');
        $table->rememberToken();
        $table->foreignId('current_team_id')->nullable();
        $table->text('profile_photo_path')->nullable();
        $table->timestamps();
    });
}

第二個是課程表：

public function up()
{
    Schema::create('courses', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->string('description');
        $table->tinyInteger('qnt_lessons');
        $table->smallInteger('qnt_hours');
        $table->string('link');
        $table->string('img')->nullable();
        $table->string('sell_link')->nullable();
        $table->timestamps();
    });
}

失敗的遷移是這個：

public function up()
{
    Schema::create('user_course', function (Blueprint $table) {
        $table->id();
        $table->unsignedBigInteger('user_id');
        $table->foreign('user_id')->reference('id')->on('users');
        $table->unsignedBigInteger('course_id');
        $table->foreign('course_id')->reference('id')->on('courses');
        $table->tinyInteger('complete_lessons')->default(0);
        $table->boolean('completed');
        $table->date('due_date');
        $table->string('buy_platform');
        $table->string('buy_status', 32)->nullable();
        $table->timestamps();
    });
}

Answer 1

問題出在語法上，你把參考和它的參考放在這里：

$table->foreign('user_id')->reference('id')->on('users');

和這里：

$table->foreign('course_id')->reference('id')->on('courses');

例如，您的代碼如下

$table->foreign('course_id')->references('id')->on('courses');

我給你留下了 laravel 的文檔，所以你可以查看

https://laravel.com/docs/8.x/migrations#foreign-key-constraints

問候。