迁移回滚后无法重新迁移 Laravel 5.2

Question

美好的一天，我是新手 laravel 我正在执行迁移回滚并且已成功完成

Rolled back: 2018_02_22_172102_adding_fk_constrains_products_to_product_types_and_service_sub_types_table

但是当我尝试重新迁移时遇到了以下错误。顺便说一句，我不想删除该列，因为它已经存在并且我不想丢失该列中的现有数据。我只想在这些表之间添加约束

[Illuminate\Database\QueryException] SQLSTATE[23000]: Integrity constraint violation: 1022 Can't write; duplicate key in table '#sql-2fc8_17c' (SQL: alter table products add constraint products_product_type_id_foreign foreign key (product_type_id) references product_types (id) on update cascade)

[PDOException] SQLSTATE[23000]: Integrity constraint violation: 1022 Can't write; duplicate key in table '#sql-2fc8_17c'

Table     Non_unique  Key_name                            Seq_in_index  Column_name
--------  ----------  ----------------------------------  ------------  -------------------
products           0  PRIMARY                                        1  id             
products           1  products_product_type_id_index                 1  product_type_id  
products           1  products_service_sub_type_id_index             1  service_sub_type_id

这是我的迁移代码

public function up()
{

    Schema::table('products',function (Blueprint $table){
        $table->integer('product_type_id')->unsigned()->index()->change();
        $table->foreign('product_type_id')->references('id')->on('product_types')->onUpdate('cascade');

        $table->integer('service_sub_type_id')->nullable()->unsigned()->index()->change();
        $table->foreign('service_sub_type_id')->references('id')->on('service_sub_types')->onUpdate('cascade');

    });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{

    Schema::table('products', function(Blueprint $table){
        $table->dropForeign(['product_type_id']);
        $table->dropForeign(['service_sub_type_id']);
    });

}

Answer 1

我只是在迁移中删除了以下代码

$table->integer('product_type_id')->unsigned()->index()->change();

$table->integer('service_sub_type_id')->nullable()->unsigned()->index()->change();

public function up()
{

   Schema::table('products',function (Blueprint $table){
      //$table->integer('product_type_id')->unsigned()->index()->change();
      $table->foreign('product_type_id')->references('id')->on('product_types')->onUpdate('cascade');

      //$table->integer('service_sub_type_id')->nullable()->unsigned()->index()->change();
      $table->foreign('service_sub_type_id')->references('id')->on('service_sub_types')->onUpdate('cascade');

});
}

当我重新迁移时，它已成功迁移..

迁移回滚后无法重新迁移 Laravel 5.2

Cannot remigrate migration after migration rollback Laravel 5.2

migration

laravel-5.2