Laravel 8 Migration "General error: 1215 Cannot add foreign key constraint"

Question

我正在尝试在 Laravel 8 上创建迁移，这是我的 table

class CreateProductVariationOrderTable extends Migration {
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('product_variation_order', function (Blueprint $table) {
            $table->integer('order_id')->unsigned()->index();
            $table->integer('product_variation_id')->unsigned()->index();
            $table->integer('quantity')->unsigned();
            $table->timestamps();

            $table->foreign('order_id')->references('id')->on('orders')->onDelete('cascade');
            $table->foreign('product_variation_id')->references('id')->on('product_variations')->onDelete('cascade');
        });
    }
    public function down()
    {
        Schema::dropIfExists('product_variation_order');
    }
}

当我运行 php artisan migrate 时，我得到了一大块错误：SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table product_variation_orderadd constraintproduct_variation_order_order_id_foreign foreign key (order_id) references 订单 (id) on delete cascade)

⚠️ 编辑：这是我的 product_variation 迁移文件。

class CreateProductVariationsTable extends Migration {
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('product_variations', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('product_id')->unsigned()->index();
            $table->string('name');
            $table->integer('price')->nullable();
            $table->integer('order')->nullable();
            $table->timestamps();

            $table->foreign('product_id')->references('id')->on('products');
        });
    }

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

Answer 1

使用此代码：

product_variations:

class CreateProductVariationsTable extends Migration {
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('product_variations', function (Blueprint $table) {
            $table->increments('id');
            $table->bigInteger('product_id')->unsigned()->nullable();
            $table->string('name');
            $table->integer('price')->nullable();
            $table->integer('order')->nullable();
            $table->timestamps();

            $table->foreign('product_id')->references('id')->on('products');
        });
    }

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

}

product_variation_order:

class CreateProductVariationOrderTable extends Migration {
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('product_variation_order', function (Blueprint $table) {
            $table->bigInteger('order_id')->unsigned()->nullable();
            $table->bigInteger('product_variation_id')->unsigned()->nullable();
            $table->integer('quantity')->unsigned();
            $table->timestamps();

            $table->foreign('order_id')->references('id')->on('orders')->onDelete('cascade');
            $table->foreign('product_variation_id')->references('id')->on('product_variations')->onDelete('cascade');
        });
    }
    public function down()
    {
        Schema::dropIfExists('product_variation_order');
    }

}

Answer 2

外键必须与引用键的类型相同。

在您的订单 table 中，您将 id 定义为 bigIncrements() 无符号大整数。

在您的 product_variation_order table 中，您将 order_id 定义为无符号整数。

所以这两个键不匹配。通常你应该使用大整数，因为它允许你的数据库变得更大，而且 space 整数和大整数之间的差异并不显着。

因此将 order_id 更改为无符号大整数。

$table->unsignedBigInteger('order_id')->nullable();

另外为了保持一致性，所有的键都应该是bigIncrements()或unsignedBigInteger()，这样以后你就不会头疼了。

Laravel 8 Migration "General error: 1215 Cannot add foreign key constraint"

Laravel 8 Migration "General error: 1215 Cannot add foreign key constraint"

php

migration

database-migration

laravel

laravel-8