mysql - 个人消息的表结构

Question

在私人消息中存储用户之间对话的最佳表结构是什么？每个用户都可以向许多收件人发送个人消息。每条消息都有发送者的标志：消息是否被删除每条消息都有接收者的标志：消息是未读、已读还是已删除每条消息都可以删除（设置标志“已删除”）

PrivateMessages 的主页应该是这样的：

例如，User1 将 Message1 发送给 User2 和 User3。在私人消息页面上，我必须显示 2 条相同的消息：

将 Message1 发送给 user2
将 Message1 发送给 user3

下一步 - User2 回复 Message2，我将在同一页面上看到以下内容：

从 user2 收到 Message2（回复 Message1）
将 Message1 发送给 user3

下一步，我回复message3，我看看

将 Message3 发送给 user2
将 Message1 发送给 user3

等等。

任何人都可以提供表格结构吗？我正在使用 MySQL 5.5

主要问题。如何仅获取每个对话框的最后一条未删除消息？

UPD。

我需要在当前用户和其他用户之间查看主页对话框列表（使用分页，按日期 DESC 排序）。

score 10 · Accepted Answer

我将首先回答您的主要问题，然后显示我将用于此的表结构。

要仅获取特定对话框的最后一条未删除消息：

select
    Message.Id
   ,Message.Subject
   ,Message.Content
from Message
join Junc_Message_To on Fk_Message = Message.Id
where Junc_Message_To.Fk_User =  {RECIPIENT_ID}
  and Message.Fk_User__From   =  {SENDER_ID}
  and Junc_Message_To.Deleted is null
order by Junc_Message_To.Sent desc
limit 1

可以使用简单的三表结构。

表 1 存储用户记录 - 每个用户一条记录。

表 2 存储消息记录 - 每条消息一条记录，外键与发送消息的用户相关。

表 3 存储了消息和收到消息的用户之间的相关性。

在此处输入图像描述

这是用于创建上述表格图的 SQL：

create table `User` (
  `Id`            int          not null auto_increment ,
  `Username`      varchar(32)  not null ,
  `Password`      varchar(32)  not null ,
  primary key     (`Id`) ,
  unique index     `Username_UNIQUE` (`Username` ASC) )
engine = InnoDB

create table `Message` (
  `Id`            int          not null auto_increment ,
  `Fk_User__From` int          not null ,
  `Subject`       varchar(256) not null ,
  `Content`       text         not null ,
  primary key   (`Id`) ,
  index          `Fk_Message_User__From` (`Fk_User__From` ASC) ,
  constraint     `Fk_Message_User__From`
    foreign key (`Fk_User__From` )
    references   `User` (`Id` )
    on delete cascade
    on update cascade)
engine = InnoDB

create table `Junc_Message_To` (
`Fk_Message`      int          not null ,
  `Fk_User`       int          not null ,
  `Sent`          datetime     not null ,
  `Read`          datetime     not null ,
  `Deleted`       datetime     not null ,
  PRIMARY KEY    (`Fk_Message`, `Fk_User`) ,
  INDEX           `Fk_Junc_Message_To__Message` (`Fk_Message` ASC) ,
  INDEX           `Fk_Junc_Message_To__User` (`Fk_User` ASC) ,
  constraint      `Fk_Junc_Message_To__Message`
    foreign key  (`Fk_Message` )
    references    `Message` (`Id` )
    on delete cascade
    on update cascade,
  constraint      `Fk_Junc_Message_To__User`
    foreign key  (`Fk_User` )
    references    `User` (`Id` )
    on delete cascade
    on update cascade)
engine = InnoDB

score 4 · Accepted Answer

过去，我使用仅包含 MessageID、ReceiverID 和 Status 的 MessageRecipient 表来完成此操作。我在那个表中也有 FolderID，但你没有这个要求。Message 表根本没有存储任何有关收件人的信息。

它是检索用户消息的连接，但确实可以防止收件人之间的消息主题和正文重复。

score 4 · Accepted Answer

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

score 1 · Accepted Answer

如果我是数据库的架构师，我会做出这样的结构（大约）

CREATE TABLE statuses(
  id INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  name VARCHAR(255) NOT NULL,
  description VARCHAR(255) DEFAULT NULL,
  PRIMARY KEY (id),
  UNIQUE INDEX name (name)
)
ENGINE = INNODB
CHARACTER SET utf8
COLLATE utf8_general_ci;

CREATE TABLE users(
  id INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  name VARCHAR(255) NOT NULL,
  PRIMARY KEY (id),
  UNIQUE INDEX name (name)
)
ENGINE = INNODB
CHARACTER SET utf8
COLLATE utf8_general_ci;

CREATE TABLE messages(
  id INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  reply_to INT(11) UNSIGNED NOT NULL,
  sender INT(11) UNSIGNED NOT NULL,
  recipient INT(11) UNSIGNED NOT NULL,
  subject VARCHAR(255) DEFAULT NULL,
  message TEXT DEFAULT NULL,
  `time` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (id),
  INDEX FK_messages_messages_id (reply_to),
  INDEX FK_messages_users_id_recipient (recipient),
  INDEX FK_messages_users_id_sender (sender),
  CONSTRAINT FK_messages_messages_id FOREIGN KEY (reply_to)
  REFERENCES messages (id) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT FK_messages_users_id_recipient FOREIGN KEY (recipient)
  REFERENCES users (id) ON DELETE NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT FK_messages_users_id_sender FOREIGN KEY (sender)
  REFERENCES users (id) ON DELETE NO ACTION ON UPDATE NO ACTION
)
ENGINE = INNODB
CHARACTER SET utf8
COLLATE utf8_general_ci;

CREATE TABLE messages_statuses(
  message_id INT(11) UNSIGNED NOT NULL,
  status_id INT(11) UNSIGNED NOT NULL,
  PRIMARY KEY (message_id, status_id),
  INDEX FK_messages_statuses_statuses_id (status_id),
  CONSTRAINT FK_messages_statuses_messages_id FOREIGN KEY (message_id)
  REFERENCES messages (id) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT FK_messages_statuses_statuses_id FOREIGN KEY (status_id)
  REFERENCES statuses (id) ON DELETE CASCADE ON UPDATE CASCADE
)
ENGINE = INNODB
CHARACTER SET utf8
COLLATE utf8_general_ci;

我在这里没有看到任何困难，但如果您有任何问题 - 请随时提问。

score 0 · Accepted Answer

id* INT, sender_id INT, recipient_id INT, message TEXT, 
flag_s_deleted = 0 TINYINT, flag_r_deleted = 0 TINYINT, flag_r_read = 0 TINYINT, 
sent_datetime DATETIME

“我怎样才能只得到每个对话框的最后一条未删除的消息？”

这个给你：

select * from (...) where 
(sender_id = ID1 and recipient_id = ID2 and flag_s_deleted = 0) 
or (sender_id = ID2 and recipient_id = ID1 and flag_r_deleted = 0) 
order by sent_date desc LIMIT 1

您 (ID1) 和其他人 (ID2) 之间的最后一条消息

score -1 · Accepted Answer

create database testMessage
go
use testMessage

go

CREATE TABLE [user] (
  userid int NOT NULL IDENTITY,
  name nvarchar(200) NOT NULL,
  PRIMARY KEY (userid)
)

go

CREATE TABLE [message] (
  msg_id int NOT NULL IDENTITY,
  userid int NOT NULL,
  msgContent nvarchar(200) NOT NULL,
  created datetime NOT NULL default getdate(),
  PRIMARY KEY (msg_id)
)

go

ALTER TABLE [message]
    ADD FOREIGN KEY (userid) REFERENCES [user](userid)
        ON DELETE CASCADE
        ON UPDATE CASCADE

go

CREATE TABLE message_folder_type (
  message_folder_type_name varchar(40) NOT NULL,
  [type] varchar(10) NOT NULL DEFAULT 'User',
  PRIMARY KEY (message_folder_type_name)
)

go

CREATE TABLE message_recipient (
  message_recipient int NOT NULL,
  userid int NOT NULL,
  message_folder_type_name varchar(40) NOT NULL,
  PRIMARY KEY (message_recipient,userid)
)

go

ALTER TABLE message_recipient
    ADD FOREIGN KEY (message_folder_type_name) REFERENCES message_folder_type(message_folder_type_name)
        ON DELETE CASCADE
        ON UPDATE CASCADE
ALTER TABLE message_recipient
    ADD FOREIGN KEY (message_recipient) REFERENCES [message](msg_id)
        ON DELETE CASCADE
        ON UPDATE CASCADE
ALTER TABLE message_recipient
    ADD FOREIGN KEY (userid) REFERENCES [user](userid)


INSERT INTO [user] VALUES ('Bob');
INSERT INTO [user] VALUES ('Harry');
INSERT INTO [user] VALUES ('Salley');
INSERT INTO [user] VALUES ('Jim');
INSERT INTO [user] VALUES ('Jake');
INSERT INTO [user] VALUES ('Randall');
INSERT INTO [user] VALUES ('Ashley');

INSERT INTO [message] VALUES ('4', 'this is a message', '2011-03-01 15:47:07');
INSERT INTO [message] VALUES ('2', 'this is a reply to message 1', '2011-03-02 15:47:28');
INSERT INTO [message] VALUES ('7', 'another cool message', '2011-03-02 15:48:15');
INSERT INTO [message] VALUES ('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');


SELECT [message].msg_id, [message].msgContent
    FROM message_recipient
    INNER JOIN message ON [message].msg_id = message_recipient.message_recipient
WHERE
    message_recipient.userid = 4
    AND message_recipient.message_folder_type_name != 'Deleted'
ORDER BY message.created DESC

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mysql - 个人消息的表结构

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