Laravel迁移-一般错误:1215无法添加外键约束

Question

我有多个带有多个外键的表，但当我迁移时，它还找不到其他迁移，因为它还没有完成。

SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table `post` add constraint `post_vote_id_foreign` foreign key (`vote_id`) references `vote` (`id`))

后表

Schema::create('post', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('topic_id');
$table->unsignedBigInteger('user_id');
$table->unsignedBigInteger('vote_id');
$table->string('title');
$table->string('summary');
$table->string('image');
$table->timestamps();
$table->foreign('topic_id')->references('id')->on('topic');
$table->foreign('user_id')->references('id')->on('users');
$table->foreign('vote_id')->references('id')->on('vote');
});

投票表查看后的所有投票

Schema::create('vote', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('post_id');
$table->unsignedBigInteger('user_id');
$table->timestamps();
$table->foreign('post_id')->references('id')->on('post');
$table->foreign('user_id')->references('id')->on('users');
});

Answer 1

尽管有循环引用并不好，但很可能表明设计不好。然而，如果你真的想有循环参考

Schema::create('post', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('topic_id');
$table->unsignedBigInteger('user_id');
$table->unsignedBigInteger('vote_id');
$table->string('title');
$table->string('summary');
$table->string('image');
$table->timestamps();
$table->foreign('topic_id')->references('id')->on('topic');
$table->foreign('user_id')->references('id')->on('users');
});

在创建投票表后，您可以更改发布表以定义外键

Schema::create('vote', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('post_id');
$table->unsignedBigInteger('user_id');
$table->timestamps();
$table->foreign('post_id')->references('id')->on('post');
$table->foreign('user_id')->references('id')->on('users');
});
Schema::table('post', function(Blueprint $table) {
$table->foreign('vote_id')->references('id')->on('vote');
});

Answer 2

需要注意的是，迁移文件按创建顺序运行。因此，请仔细检查您的表设计，先获得那些独立的表(更改它们的文件名，即时间戳，使它们先出现(，然后再获得依赖的表(具有独立表外键的表(。我希望你能理解？

Answer 3

对于谷歌人。。。在我的情况下，这是因为父表是myIsam类型，而不是innodb