创建带有两个时间戳列的表时出现Laravel错误

我在Laravel 6.6中使用以下定义创建了一个表。

public function up()
{
    Schema::create('quarters', function (Blueprint $table) {
        $table->integer('quarter_id')->unsigned();
        $table->integer('year')->unsigned();
        $table->integer('quarter_num')->unsigned();
        $table->timestamp('valid_from');
        $table->timestamp('valid_to'); // <------ error on this line
        $table->string('description')->nullable();
        $table->timestamps();
        $table->primary('quarter_id');
    });
} 

当我运行迁移命令时，出现以下错误。

Illuminate \ Database \ QueryException：SQLSTATE [42000]：语法错误或访问冲突：1067“ valid_to”的默认值无效（SQL：创建表quarters（quarter_idint unsigned not null，yearint unsigned not null，quarter_numint unsigned not null，valid_fromtimestamp not null，valid_to时间戳记不为null，descriptionvarchar（255）为null，created_at时间戳为null，updated_at时间戳为null）默认字符集utf8mb4整理为'utf8mb4_unicode_ci'）

这是Eloquent生成的SQL：

CREATE TABLE `quarters`(
    `quarter_id` INT UNSIGNED NOT NULL,
    `year` INT UNSIGNED NOT NULL,
    `quarter_num` INT UNSIGNED NOT NULL,
    `valid_from` TIMESTAMP NOT NULL,
    `valid_to` TIMESTAMP NOT NULL,
    `description` VARCHAR(255) NULL,
    `created_at` TIMESTAMP NULL,
    `updated_at` TIMESTAMP NULL
) DEFAULT CHARACTER SET utf8mb4 COLLATE 'utf8mb4_unicode_ci'

奇怪的是，如果我注释掉该valid_to行，它将创建没有错误的表。但是的定义与valid_to100％相似valid_from，并且不会为该valid_from列引发该错误。实际上，似乎数据库不允许两timestamp列！

根据评论中的要求，我运行了php artisan migrate --pretend，结果如下：

C:\xampp\htdocs\voiceit> php artisan migrate --pretend
CreateQuartersTable: create table `quarters` (`quarter_id` int unsigned not null, `year` int unsigned not null, `quarter_num` int unsigned not null, `valid_from` timestamp not null, `valid_to` timestamp not null, `description` varchar(255) null, `created_at` timestamp null, `updated_at` timestamp null) default character set utf8mb4 collate 'utf8mb4_unicode_ci'
CreateQuartersTable: alter table `quarters` add primary key `quarters_quarter_id_primary`(`quarter_id`)
CreatePeopleDatasTable: create table `people_datas` (`mt_id` bigint unsigned not null, `valid_for` int unsigned not null, `local_personal_id` bigint unsigned not null, `first_name` varchar(255) not null, `last_name` varchar(255) not null, `date_of_birth` date null, `date_of_join` date null, `gender` varchar(1) not null, `location_type` varchar(1) not null, `created_at` timestamp null, `updated_at` timestamp null, `deleted_at` timestamp null) default character set utf8mb4 collate 'utf8mb4_unicode_ci'
CreatePeopleDatasTable: alter table `people_datas` add primary key `people_datas_mt_id_valid_for_primary`(`mt_id`, `valid_for`)
CreatePeopleDatasTable: alter table `people_datas` add constraint `people_datas_valid_for_foreign` foreign key (`valid_for`) references `quarters` (`quarter_id`)
CreatePeopleDatasTable: alter table `people_datas` add constraint `people_datas_gender_foreign` foreign key (`gender`) references `genders` (`id`)
CreatePeopleDatasTable: alter table `people_datas` add constraint `people_datas_location_type_foreign` foreign key (`location_type`) references `location_types` (`id`)
CreatePeopleDatasTable: alter table `people_datas` add index `people_datas_last_name_index`(`last_name`)