MariaDB [test]> create table users (id bigint unsigned NOT NULL primary key)engine=innodb;

Query OK, 0 rows affected (0.025 sec)

MariaDB [test]> create table `test` (`id` bigint unsigned not null auto_increment primary key, `user_id` bigint unsigned not null, `additionalData` json null, `created_at` timestamp null, `updated_at` timestamp null) engine=innodb default character set utf8mb4 collate 'utf8mb4_unicode_ci';

Query OK, 0 rows affected (0.025 sec)

MariaDB [test]> alter table `test` add constraint `test_user_id_foreign` foreign key (`user_id`) references `users` (`id`) on delete cascade;

Query OK, 0 rows affected (0.127 sec)              

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table test;

+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |

+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| test  | CREATE TABLE `test` (

  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,

  `user_id` bigint(20) unsigned NOT NULL,

  `additionalData` longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(`additionalData`)),

  `created_at` timestamp NULL DEFAULT NULL,

  `updated_at` timestamp NULL DEFAULT NULL,

  PRIMARY KEY (`id`),

  KEY `test_user_id_foreign` (`user_id`),

  CONSTRAINT `test_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci |

+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

1 row in set (0.001 sec)

MariaDB [test]> select version();

+-----------------+

| version()       |

+-----------------+

| 10.4.10-MariaDB |

+-----------------+

1 row in set (0.000 sec)