消息被广播给用户。因此在更新表中只创建一条消息记录。如何从mysql获取未读消息
table name : updates
id :
title : message
user_id : created user id
table name : message _status
id
message_id
user_id : read by user
如果有用户读取消息,我们在updates_status表中输入条目。
我想显示未读消息列表,这些消息不是由当前用户创建并且未读。这里是我的查询:
select u.*, s.user_id as status_user, s.id
from updates as u left outer join update_status as s ON u.id=s.update_id
where u.user_id != 1 and (s.user_id is null or s.user_id != 1)
我收到6条,而不是5
这里从fiddle的DDL:
CREATE TABLE IF NOT EXISTS `users` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`u_name` varchar(100) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;
--
-- Dumping data for table `users`
--
INSERT INTO `users` (`id`, `u_name`) VALUES
(1, 'Praveen'),
(2, 'Ravi'),
(3, 'Ram'),
(4, 'Mohan');
CREATE TABLE IF NOT EXISTS `updates` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(200) DEFAULT NULL,
`user_id` int(11) DEFAULT NULL,
`created` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=7 ;
--
-- Dumping data for table `updates`
--
INSERT INTO `updates` (`id`, `title`, `user_id`, `created`) VALUES
(1, 'message1', 2, '2015-09-28 15:50:38'),
(2, 'message2', 2, '2015-09-28 15:50:38'),
(3, 'message3', 1, '2015-09-28 17:00:37'),
(4, 'message4', 1, '2015-09-28 17:00:37'),
(5, 'message5', 3, '2015-09-28 17:05:21'),
(6, 'message6', 4, '2015-09-28 17:05:21');
CREATE TABLE IF NOT EXISTS `update_status` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`update_id` int(11) NOT NULL,
`user_id` int(11) NOT NULL,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=7 ;
--
-- Dumping data for table `update_status`
--
INSERT INTO `update_status` (`id`, `update_id`, `user_id`, `created`) VALUES
(2, 1, 1, '2015-09-28 17:02:15'),
(3, 3, 2, '2015-09-28 17:04:16'),
(4, 1, 3, '2015-09-28 17:06:24'),
(5, 1, 4, '2015-09-28 17:06:33'),
(6, 3, 3, '2015-09-28 17:17:12');
我想获取当前用户的未读消息。 –
请张贴你的最终结果应该来自你发布的那些值吗? –
我想创建此消息的update.id,update.title和用户名 –