errno: 150 外键约束的格式不正确

Question

我有 laravel 5.5 个项目在迁移中我写了这个

Schema::create('item_gifts', function (Blueprint $table) {
    $table->increments('id');
    $table->string('item_gift_name');
    $table->integer('item_gift_item_id_from')->unsigned();
    $table->foreign('item_gift_item_id_from')->references('id')->on('items');           
    $table->integer('item_gift_item_id_to')->unsigned();
    $table->foreign('item_gift_item_id_to')->references('id')->on('items');             
    $table->integer('item_gift_quantity');
    $table->integer('item_gift_min_order');
    $table->timestamps();
});

但我总是遇到这个错误

In Connection.php line 664:

  SQLSTATE[HY000]: General error: 1005 Can't create table `lar
  avel`.`#sql-2830_22f` (errno: 150 "Foreign key constraint is
   incorrectly formed") (SQL: alter table `item_gifts` add con
  straint `item_gifts_user_id_foreign` foreign key (`user_id`)
   references `items` (`id`))


In Connection.php line 458:

  SQLSTATE[HY000]: General error: 1005 Can't create table `lar
  avel`.`#sql-2830_22f` (errno: 150 "Foreign key constraint is
   incorrectly formed")

我需要的是将 item_gifts 中的 item_gift_item_id_from 与项目中的 id 连接起来我尝试了很多解决方案，但没有任何效果谢谢..

Answer 1

试试这个代码：

public function up()
{
Schema::create('item_gifts', function($table) {
   $table->increments('id');
   $table->string('item_gift_name');
   $table->integer('item_gift_item_id_from')->unsigned();
   $table->integer('item_gift_item_id_to')->unsigned();
   $table->integer('item_gift_quantity');
   $table->integer('item_gift_min_order');
   $table->timestamps();
});

  Schema::table('item_gifts', function($table) {
   $table->foreign('item_gift_item_id_from')->references('id')->on('items');           
  $table->foreign('item_gift_item_id_to')->references('id')->on('items'); 
 });

}

Answer 2

您收到此错误，因为您手动创建了项目 table，其中 ID 只是一个整数：

CREATE TABLE items ( id int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

创建新迁移并使其在 item_gists 之前执行：

Schema::create('item_gifts', function (Blueprint $table) {
    $table->increments('id');
});

errno: 150 外键约束的格式不正确

errno: 150 Foreign key constraint is incorrectly formed

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