Laravel 创建具有两个时间戳列的表时出错

我在 Laravel 6.6 中创建了一个具有以下定义的表。

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 无符号不为空，year无符号整型 不为空，quarter_numint 无符号不为空，valid_from时间戳不为空，valid_to时间戳不为空，descriptionvarchar(255) 空，created_at时间戳为空，updated_at时间戳 null) 默认字符集 utf8mb4 collat​​e '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valid_to行，然后它会毫无错误地创建表。但定义valid_to100%相似于valid_from，并且它不会抛出该错误valid_from柱子。实际上，数据库似乎不允许两个timestamp列！

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

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`)

我通过更改列的类型解决了我的问题timestamp to dateTime。因此，如下更改表定义解决了我的问题，因为我需要日期和时间：

Schema::create('quarters', function (Blueprint $table) {
             $table->integer('quarter_id')->unsigned();
             $table->integer('year')->unsigned();
             $table->integer('quarter_num')->unsigned();
             $table->dateTime('valid_from');
             $table->dateTime('valid_to');            
             $table->string('description')->nullable();
             $table->timestamps();
             $table->primary('quarter_id');
        });

但是，我仍然有兴趣知道我们如何才能拥有多个not null表中的时间戳列。