如何为每个冠军选择当前的持有人？

championships

NULL

CREATE TABLE `championships` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `friendly_name` varchar(255) NOT NULL,
  `rank` int(2) unsigned NOT NULL DEFAULT \'1\',
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`),
  UNIQUE KEY `friendly_name` (`friendly_name`)
) ENGINE=InnoDB;

CREATE TABLE `title_history` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `championship` int(10) unsigned NOT NULL,
  `winner` varchar(255) NOT NULL,
  `date_from` date NOT NULL,
  `location` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `championship` (`championship`)
) ENGINE=InnoDB;

ALTER TABLE `title_history` ADD CONSTRAINT `title_history_ibfk_1` FOREIGN KEY (`championship`) REFERENCES `championships` (`id`) ON UPDATE CASCADE;