PHP 自定义聊天，编码 block 功能

Question

我曾尝试构建一个 Block 函数，但没有任何运气，我的 SQL 技能在这种情况下不如我希望的那么好。

我有一张名为“消息”的表和一张名为“ block ”的表 现在，有 1 个文件将所有内容同步到聊天，我想做的是，如果用户 1 阻止了用户 2，那么用户 1 的消息永远不会到达用户 2，用户 2 的消息不应该到达用户 1。短期内，如果你屏蔽了一个你不能和他/她说话的人，他/她也不能和你说话!

"blocks" table:
id bigint(20)
user_id tinyint(20)
block_id tinyint(20)

"messages" table:
id bigint(20)
timestamp datetime
dest_type varchar(255)
dest_id bigint(20)
source_type varchar(255)
source_id bigint(20)
message_type varchar(255)
message text

在“ block ”中，user_id 是 block 行的所有者 ID。 block_id 是所有者想要阻止的 id。 IF "messages.source_id = blocks.block_id OR messages.block_id = blocks.user_id" 不要让消息传播出去。我知道让别人为我编写代码是很粗鲁的，但我想问一下，有人可以试一试吗？

这是 sync.php 文件: http://pastebin.com/8iiSCXGS

非常感谢!

Answer 1

我没有深入研究您的代码，但也许这会有所帮助。

让我们从简化的数据库结构开始，如下所示:

CREATE TABLE `blocks` (
  `id`            BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `user_id`       INT UNSIGNED NOT NULL,
  `block_id`      INT UNSIGNED NOT NULL );

INSERT INTO `blocks` (`user_id`,`block_id`) VALUES
  (1,2),(3,4),(2,1);

CREATE TABLE `messages` (
  `id`            BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `author_id`     BIGINT NOT NULL,
  `message`       TEXT NOT NULL );

INSERT INTO `messages` (`author_id`,`message`) VALUES
  (1,"Message from user #1, who has a mutual block in place with user #2"),
  (2,"Message from user #2, who has a mutual block in place with user #1"),
  (3,"Message from user #3, who has blocked user #4"),
  (4,"Message from user #4, who has been blocked by user #3"),
  (5,"Message from user #5, who takes no part in all this blocking business");

现在假设用户 $n访问网站(其中 1≤ $n ≤5)。为了弄清楚可以显示哪些消息，我们需要执行 messages 的左连接。和 blocks表——即我们要考虑 messages 的每一行连同任何一行 blocks包含相关信息(具体而言，消息的作者已阻止用户 $n 或已被用户 $n 阻止)。如果$n =1，我们有以下内容:

SELECT * FROM `messages`
  LEFT JOIN `blocks`
    ON (`author_id`=`block_id` AND `user_id`=1)
    OR (`author_id`=`user_id` AND `block_id`=1);

这是该查询的结果:

+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
| id | author_id | message                                                               | id   | user_id | block_id |
+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
|  1 |         1 | Message from user #1, who has a mutual block in place with user #2    | NULL |    NULL |     NULL |
|  2 |         2 | Message from user #2, who has a mutual block in place with user #1    |    1 |       1 |        2 |
|  2 |         2 | Message from user #2, who has a mutual block in place with user #1    |    3 |       2 |        1 |
|  3 |         3 | Message from user #3, who has blocked user #4                         | NULL |    NULL |     NULL |
|  4 |         4 | Message from user #4, who has been blocked by user #3                 | NULL |    NULL |     NULL |
|  5 |         5 | Message from user #5, who takes no part in all this blocking business | NULL |    NULL |     NULL |
+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
6 rows in set (0.00 sec)

如您所见，我们想要的行是最后三列为 NULL 的行，这意味着没有阻止规则影响向该特定用户显示该特定消息。所以要提取这些消息，我们只需添加 WHERE <code>block_id</code> IS NULL到查询的末尾:

SELECT * FROM `messages`
  LEFT JOIN `blocks`
    ON (`author_id`=`block_id` AND `user_id`=1)
    OR (`author_id`=`user_id` AND `block_id`=1)
  WHERE `block_id` IS NULL;
+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
| id | author_id | message                                                               | id   | user_id | block_id |
+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
|  1 |         1 | Message from user #1, who has a mutual block in place with user #2    | NULL |    NULL |     NULL |
|  3 |         3 | Message from user #3, who has blocked user #4                         | NULL |    NULL |     NULL |
|  4 |         4 | Message from user #4, who has been blocked by user #3                 | NULL |    NULL |     NULL |
|  5 |         5 | Message from user #5, who takes no part in all this blocking business | NULL |    NULL |     NULL |
+----+-----------+-----------------------------------------------------------------------+------+---------+----------+
4 rows in set (0.01 sec)

如果您在此查询中替换不同的用户 ID，您应该会得到想要的结果。