CREATE TABLE `transactions` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `community_id` int(10) unsigned NOT NULL,
  `currency_id` int(10) unsigned NOT NULL,
  `payer_user_id` int(10) unsigned NOT NULL,
  `payee_user_id` int(10) unsigned NULL,
  `description` varchar(255) NOT NULL,
  `sum` decimal(19,9) NOT NULL,
  `time` timestamp NOT NULL DEFAULT current_timestamp(),
  PRIMARY KEY (`id`),
  KEY `community_id` (`community_id`),
  KEY `currency_id` (`currency_id`),
  KEY `payer_user_id` (`payer_user_id`),
  KEY `payee_user_id` (`payee_user_id`),
  CONSTRAINT `transactions_community_id` FOREIGN KEY (`community_id`) REFERENCES `communities` (`id`),
  CONSTRAINT `transactions_currency_id` FOREIGN KEY (`currency_id`) REFERENCES `currencies` (`id`),
  CONSTRAINT `transactions_payer_user_id` FOREIGN KEY (`payer_user_id`) REFERENCES `users` (`id`),
  CONSTRAINT `transactions_payee_user_id` FOREIGN KEY (`payee_user_id`) REFERENCES `users` (`id`)
) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;