我在MySQL Server 5.5上遇到了截断表的问题。
我尝试截断的表中有一列在另一个表中作为外键使用。
两个涉及表的CREATE TABLE
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
。当我尝试
TRUNCATE
表格时:TRUNCATE TABLE `<databasename>`.`tbluser`;
我收到以下错误信息:
Cannot truncate a table referenced in a foreign key constraint
(`<databasename>`.`tblpost`,
CONSTRAINT `FK_tblpost_updateUserId`
FOREIGN KEY (`updateUserId`)
REFERENCES `<databasename>`.`tbluser` (`id`))
除了这些信息外,还有一个事实,当尝试在MySQL Server 5.1上执行上述操作时,它是有效的!有人知道为什么会发生这种情况吗?