mysql - 用于聊天的复杂 Mysql 查询，按 desc 排序，最后留下 NULL

Question

我有两个表 sms_contacts 和 sms_twoway_chat。联系人表使用 id 作为 PK，contact_type 用于 3 种 psooible 类型的联系人(0,1 和 2)sms_twoway_chat 保存两个联系人之间的所有聊天。

我需要 contact_type 0 的所有联系人，无论他们是否有聊天我只需要 contact_type 1 和 2 且已收到回复的联系人我需要未读 (is_read = 0) 和最近的聊天回复 (date_time desc ) 位于顶部

我所做的是在顶部显示 Null，例如聊天表中没有任何记录的类型 0 的联系人显示在顶部，而他们应该在最后

CREATE TABLE IF NOT EXISTS `sms_contacts` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) DEFAULT NULL,
  `contacts_name` varchar(50) DEFAULT NULL,
  `contacts_phone` varchar(11) DEFAULT NULL,
  `date_time` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
  `date_time_unix` bigint(20) DEFAULT NULL,
  `contact_type` int(1) DEFAULT '0' COMMENT '0=>contact 1=>group , 2=>instant msg',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=19 ;


CREATE TABLE IF NOT EXISTS `sms_twoway_chat` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `inbound_id` varchar(50) DEFAULT NULL,
  `sender_id` int(11) DEFAULT NULL,
  `receiver_id` int(11) DEFAULT NULL,
  `is_read` int(1) DEFAULT '0',
  `msg_body` text,
  `date_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `date_time_unix` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=89 ;

这是我尝试过的

SELECT a.*
  FROM ( SELECT c.id,c.`contacts_name` FROM sms_contacts c
LEFT JOIN sms_twoway_chat tc ON c.id = tc.`receiver_id`
WHERE user_id = 1 AND c.contact_type = 0
ORDER BY -tc.`is_read`,  tc.date_time DESC
       ) a
 UNION
SELECT b.*
  FROM ( SELECT c.id,c.`contacts_name` FROM sms_contacts c
INNER JOIN sms_twoway_chat tc  ON c.id = tc.`receiver_id`
WHERE user_id = 1 AND c.contact_type IN(1,2)
ORDER BY -tc.`is_read`,tc.date_time DESC
       ) b;

What about this as a solution ??

SELECT *
    FROM (
        SELECT c.id AS i,  1 AS dt
        FROM sms_contacts c 
        WHERE user_id = 1 AND c.contact_type = 0
    ) t1 
LEFT  JOIN 
(SELECT *
    FROM (
        SELECT DISTINCT sender_id AS i, MAX(date_time) AS dt
        FROM sms_twoway_chat 
        WHERE `inbound_id` <> "" AND `receiver_id` =1
        GROUP BY sender_id 
        ORDER BY MAX(date_time) DESC, sender_id
    )t3 )t2
ON t1.i = t2.i
ORDER BY t2.dt DESC

Answer 1

这可能对某人有帮助

SELECT *
    FROM (
        SELECT c.id AS i,  1 AS dt, c.`contacts_name`
        FROM sms_contacts c
        WHERE user_id = 1 AND c.contact_type = 0
    ) t1
LEFT  JOIN
(SELECT *
    FROM (
        SELECT DISTINCT sender_id AS i, MAX(date_time) AS dt, 2 AS contacts_name

        FROM sms_twoway_chat
        WHERE `inbound_id` <> "" AND `receiver_id` =1
        GROUP BY sender_id
        ORDER BY MAX(date_time) DESC, sender_id
    )t3 )t2
ON t1.i = t2.i
ORDER BY t2.dt DESC LIMIT 0,100