Question

我在mysql数据库中有3个表

chat
user1, user2, chat_key

chat_seen
msgid, userid, viewed

users
username, status, key

所以我试图显示用户在线排序聊天然后看到的消息。但它不起作用。这就是我到目前为止，iv只是让它与聊天和用户一起工作，我不知道如何通过聊天添加订单

("SELECT u.random, u.status, c.chat_key, c.seen, u.username
                                     FROM chat c, users u
                                     WHERE CASE 
                                     WHEN c.user1 = ?
                                     THEN c.user2 = u.random
                                     WHEN c.user2 = ?
                                     THEN c.user1= u.random
                                     END 
                                     AND (
                                     c.user1 = ?
                                     OR c.user2 = ?)
                                     ORDER BY u.status DESC LIMIT 50");

所以结果应该是

username - online - (2 messages)
username - online - (1 message)

username - offline - (20 messages)
username - offline - (2 messages)
username - offline - (o messages)

目前我

username - online - (0 messages)
username - online - (0 messages)
username - offline - (2messages)
username - offline - 20 messages)

Answer 1

请尝试以下查询：

("SELECT 
u.random, 
u.status, 
c.chat_key, 
c.seen, 
u.username

FROM chat c, users u

WHERE 
(c.user1 = ? AND c.user2 = u.random)
OR
 (c.user2 = ? AND c.user1 = u.random)
AND 
(c.user1 = ? OR c.user2 = ?)

ORDER BY u.status DESC LIMIT 50");

让我知道它是否有效。：d

mysql连接无法正常工作

1 个答案: