尝试截断表时出现MySQL错误

Question

我在MySQL Server 5.5上截断表时遇到问题.

我正在尝试截断的表有一列作为另一个表中的外键.

在CREATE TABLE涉及两个表是因为它如下:

CREATE TABLE `tbluser` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `email` varchar(255) NOT NULL,
  `password` varchar(255) NOT NULL,
  `name` varchar(255) NOT NULL,
  `creationDate` datetime NOT NULL,
  `creationUserId` int(11) NOT NULL,
  `updateDate` datetime NOT NULL,
  `updateUserId` int(11) NOT NULL,
  `lastAccess` datetime NOT NULL,
  `enabled` tinyint(1) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `id_UNIQUE` (`id`),
  UNIQUE KEY `email_UNIQUE` (`email`),
  KEY `FK_tbluser_creationUserId` (`creationUserId`),
  KEY `FK_tbluser_updateUserId` (`updateUserId`),
  CONSTRAINT `FK_tbluser_updateUserId` FOREIGN KEY (`updateUserId`) REFERENCES `tbluser` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `FK_tbluser_creationUserId` FOREIGN KEY (`creationUserId`) REFERENCES `tbluser` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;

CREATE TABLE `tblpost` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) NOT NULL,
  `content` mediumtext NOT NULL,
  `creationDate` datetime NOT NULL DEFAULT '1901-01-01 00:00:00',
  `creationUserId` int(11) NOT NULL,
  `updateDate` datetime NOT NULL DEFAULT '1901-01-01 00:00:00',
  `updateUserId` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_tblpost_creationUserId` (`creationUserId`),
  KEY `FK_tblpost_updateUserId` (`updateUserId`),
  CONSTRAINT `FK_tblpost_updateUserId` FOREIGN KEY (`updateUserId`) REFERENCES `tbluser` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `FK_tblpost_creationUserId` FOREIGN KEY (`creationUserId`) REFERENCES `tbluser` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

请注意,所有约束都设置为DELETE和UPDATE ON CASCADE.

当我试着去TRUNCATE桌子时:

TRUNCATE TABLE `<databasename>`.`tbluser`;

我收到以下错误消息:

Cannot truncate a table referenced in a foreign key constraint
(`<databasename>`.`tblpost`, 
CONSTRAINT `FK_tblpost_updateUserId` 
FOREIGN KEY (`updateUserId`) 
REFERENCES `<databasename>`.`tbluser` (`id`))

除了这些信息之外,还有一个事实是,当在MySQL Server 5.1上尝试上述操作时,它可以工作!

有没有人知道为什么会这样？

Answer 1

检查这里。在这种情况下，这是有道理的，TRUNCATE TABLE会引发错误；坏事是没有记录下来。