根据您提供的信息,这是我的方法。
用户表是一个让步。我的只是id
和name
。
我们显然需要一个表来存储消息。我们需要知道是谁author
编辑了它,它subject
的message
内容,以及(可能)它是什么时候created
/发送的。
我们需要知道是谁message_recipients
。从技术上讲,甚至message.author
会发送一个副本message
(在大多数情况下),但它通常放在一个folder='Sent'
. 其他人可能都在他们的folder="Inbox"
. 然后,用户可以将其message
移至他们的位置folder='Trash'
或将其完全删除。如果由于某种原因您需要在用户删除消息后保留它们,您可以通过folder='Deleted'
使用folder.type='System'
. 如果没有,只需删除该message_recipients
表中的记录message_recipient.user
。
所以这里是相关的信息。在模式和数据之后查询的测试用例。
架构:
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`name` tinytext NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;
CREATE TABLE `message` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`author` int(11) unsigned NOT NULL,
`subject` varchar(255) NOT NULL,
`message` mediumtext NOT NULL,
`created` datetime NOT NULL,
PRIMARY KEY (`id`),
KEY `fk_m_author` (`author`),
CONSTRAINT `fk_m_author` FOREIGN KEY (`author`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
DROP TABLE IF EXISTS `message_folder_type`;
CREATE TABLE `message_folder_type` (
`name` varchar(40) NOT NULL,
`type` enum('System','User') NOT NULL DEFAULT 'User',
PRIMARY KEY (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
DROP TABLE IF EXISTS `message_recipient`;
CREATE TABLE `message_recipient` (
`message` int(11) unsigned NOT NULL,
`user` int(11) unsigned NOT NULL,
`folder` varchar(40) NOT NULL,
PRIMARY KEY (`message`,`user`),
KEY `fk_mr_user` (`user`),
KEY `fk_mr_message_folder` (`folder`),
CONSTRAINT `fk_mr_message_folder` FOREIGN KEY (`folder`) REFERENCES `message_folder_type` (`name`) ON UPDATE CASCADE,
CONSTRAINT `fk_mr_message` FOREIGN KEY (`message`) REFERENCES `message` (`id`) ON UPDATE CASCADE,
CONSTRAINT `fk_mr_user` FOREIGN KEY (`user`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
测试数据:
INSERT INTO `user` VALUES ('1', 'Bob');
INSERT INTO `user` VALUES ('2', 'Harry');
INSERT INTO `user` VALUES ('3', 'Salley');
INSERT INTO `user` VALUES ('4', 'Jim');
INSERT INTO `user` VALUES ('5', 'Jake');
INSERT INTO `user` VALUES ('6', 'Randall');
INSERT INTO `user` VALUES ('7', 'Ashley');
INSERT INTO `message` VALUES ('1', '4', 'Message 1', 'this is a message', '2011-03-01 15:47:07');
INSERT INTO `message` VALUES ('2', '2', 'Message 2', 'this is a reply to message 1', '2011-03-02 15:47:28');
INSERT INTO `message` VALUES ('3', '7', 'Message 3', 'another cool message', '2011-03-02 15:48:15');
INSERT INTO `message` VALUES ('4', '4', 'Message 4', 'blah blah blah Sally', '2011-03-09 15:48:43');
INSERT INTO `message_folder_type` VALUES ('Deleted', 'System');
INSERT INTO `message_folder_type` VALUES ('Inbox', 'User');
INSERT INTO `message_folder_type` VALUES ('Sent', 'User');
INSERT INTO `message_folder_type` VALUES ('Trash', 'User');
INSERT INTO `message_recipient` VALUES ('1', '1', 'Inbox');
INSERT INTO `message_recipient` VALUES ('1', '2', 'Inbox');
INSERT INTO `message_recipient` VALUES ('2', '4', 'Inbox');
INSERT INTO `message_recipient` VALUES ('2', '5', 'Inbox');
INSERT INTO `message_recipient` VALUES ('3', '5', 'Inbox');
INSERT INTO `message_recipient` VALUES ('1', '4', 'Sent');
INSERT INTO `message_recipient` VALUES ('2', '2', 'Sent');
INSERT INTO `message_recipient` VALUES ('3', '7', 'Sent');
INSERT INTO `message_recipient` VALUES ('4', '4', 'Sent');
INSERT INTO `message_recipient` VALUES ('1', '3', 'Trash');
INSERT INTO `message_recipient` VALUES ('4', '3', 'Trash');
测试用例:获取每个对话框的最后一个未删除的消息
我不完全确定这意味着什么,但我会假设“在给定用户的收件箱中”和“不在系统已删除文件夹中”作为我查询的一部分。
SELECT message.`subject`, message.message, message.`author`
FROM message_recipient
INNER JOIN message ON message.id = message_recipient.message
WHERE
message_recipient.user = 4
AND message_recipient.folder != 'Deleted'
ORDER BY message.created DESC
根据提供的测试数据,这给出了以下结果:
Subject Message Author
Message 4 blah blah blah Sally 4
Message 2 this is a reply to message 1 2
Message 1 this is a message 4