CREATE TABLE `currencies` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `community_id` int(10) unsigned NOT NULL,
  `code` varchar(3) NOT NULL,
  `round_digits` tinyint(1) unsigned NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `unique_currency_for_community` (`community_id`, `code`),
  KEY `community_id` (`community_id`),
  CONSTRAINT `currencies_community_id` FOREIGN KEY (`community_id`) REFERENCES `communities` (`id`)
) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;