Question

In Connection.php line 664:
  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table `point_deliveries` add constraint `point_d
  eliveries_city_ref_foreign` foreign key (`city_ref`) references `cities` (`ref`))

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

我链接了表格，所以...

//parent
Schema::create('cities', function(Blueprint $table)
        {
            $table->increments('id');
            $table->string('title')->nullable();
            $table->string('ref');
            $table->integer('country_id')->index()->unsigned()->nullable();
            $table->foreign('country_id')->references('id')->on('countries');
        });

//child
Schema::create('point_deliveries', function (Blueprint $table)
        {
            $table->increments('id');
            $table->string('title')->nullable();
            $table->string('ref')->nullable();
            $table->string('city_ref');
            $table->foreign('city_ref')->references('ref')->on('cities');
        });

如何系好它们？字段整数没有问题。

Answer 1

您只能有一个引用唯一字段的外键。修改您的城市表，使ref字段唯一，如下所示：

// cities

$table->string('ref')->unique();

Answer 2

列必须被索引

为了创建外键约束，必须对要链接到的表上的列建立索引。我建议您在城市表上使ref字段唯一，从而为其指定索引，并确保仅链接一个项目。

//parent
Schema::create('cities', function(Blueprint $table)
        {
            $table->increments('id');
            $table->string('title')->nullable();
            $table->string('ref')->unique();;
            $table->integer('country_id')->index()->unsigned()->nullable();
            $table->foreign('country_id')->references('id')->on('countries');
        });

//child
Schema::create('point_deliveries', function (Blueprint $table)
        {
            $table->increments('id');
            $table->string('title')->nullable();
            $table->string('ref')->nullable();
            $table->string('city_ref');
            $table->foreign('city_ref')->references('ref')->on('cities');
        });

Answer 3

确保默认情况下将表引擎设置为InnoDB，或者使用$ table-> engine ='InnoDB';显式设置它。

这也是5.8的文档，希望对您有所帮助。

https://laravel.com/docs/5.8/migrations

字段类型为字符串SQLSTATE [HY000]时出现迁移问题：常规错误：1215

3 个答案:

列必须被索引