在 phpMyAdmin 中消失的外键
我正在 mysql 中创建一个新表,并尝试向其中一个字段添加外键约束.
<前>创建表`在线订单`(`receiptid` varchar(10) NOT NULL 默认值 '',`delivereddate` 日期默认为 NULL,`cid` int(10) 非空,`card#` int(10) 默认为 NULL,`expire` 日期默认为 NULL,主键(`receiptid`),FOREIGN KEY (receiptid) REFERENCES 购买) 引擎=MyISAM 默认字符集=latin1;但是,在它创建之后,我进入 phpMyAdmin 并导出表.外键约束似乎已经消失了.
<前>创建表`在线订单`(`receiptid` varchar(10) NOT NULL 默认值 '',`delivereddate` 日期默认为 NULL,`cid` int(10) 非空,`card#` int(10) 默认为 NULL,`expire` 日期默认为 NULL,主键(`receiptid`)) 引擎=MyISAM 默认字符集=latin1;phpMyAdmin 是否去掉了外键,还是我在这里做错了什么?
解决方案需要使用InnoDB引擎才能有外键.
参考:http://dev.mysql.com/doc/refman/5.0/en/innodb-foreign-key-constraints.html
I am creating a new table inside mysql and I am trying to add a foreign key constraint to one of the fields.
CREATE TABLE `onlineorder` ( `receiptid` varchar(10) NOT NULL default '', `delivereddate` date default NULL, `cid` int(10) NOT NULL, `card#` int(10) default NULL, `expire` date default NULL, PRIMARY KEY (`receiptid`), FOREIGN KEY (receiptid) REFERENCES purchase ) ENGINE=MyISAM DEFAULT CHARSET=latin1;
However, after it creates it, I go into phpMyAdmin and export the table. and it seems like the foreign key constraint has disappeared.
CREATE TABLE `onlineorder` ( `receiptid` varchar(10) NOT NULL default '', `delivereddate` date default NULL, `cid` int(10) NOT NULL, `card#` int(10) default NULL, `expire` date default NULL, PRIMARY KEY (`receiptid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1;
Does phpMyAdmin get rid of foreign keys or am I doing something wrong here?
解决方案You need to use the InnoDB engine to have foreign keys.
Ref: http://dev.mysql.com/doc/refman/5.0/en/innodb-foreign-key-constraints.html
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