我对PHP和MySQL都很陌生。我有几个问题，我几乎可以肯定是由一个函数引起的：
function fetch_conversation_summary(){
$sql = "SELECT
`conversations`.`conversation_id`,
`conversations`.`conversation_subject`,
MAX(`conversations_messages`.`message_date`) AS `conversation_last_reply`,
MAX(`conversations_messages`.`message_date`) > `conversations_members`.`conversation_last_view` AS `conversation_unread`
FROM `conversations`
LEFT JOIN `conversations_messages` ON `conversations`.`conversation_id` = `conversations_messages`.`conversation_id`
INNER JOIN `conversations_members` ON `conversations`.`conversation_id` = `conversations_messages`.`conversation_id`
WHERE `conversations_members`.`user_id` = {$_SESSION['user_id']}
AND `conversations_members`.`conversation_deleted` = 0
GROUP BY `conversations`.`conversation_id`
ORDER BY `conversation_last_reply` DESC";
$result = mysql_query($sql);
$conversations = array();
while (($row = mysql_fetch_assoc($result)) !== false){
$conversations[] = array(
'id' => $row['conversation_id'],
'subject' => $row['conversation_subject'],
'last_reply' => $row['conversation_last_reply'],
'unread_messages' => ($row['conversation_unread'] == 1),
);
}
return $conversations;
}
我花了很长时间试图调试它。这显然会影响一些事情，因为某些错误有时会发生，有时却不会发生：
1）只能删除热门会话 - 其他会话是“会话ID无效”。然后，当新消息发送给删除顶部消息的人时，所有消息都会重新出现
2）消息仅出现在发送者（不是收件人）的收件箱中
3）每个人都会看到消息
4）应该有效的消息将获得“无效的会话ID”
并非所有这些都会一直发生，但使用相同的代码，至少会发生其中一个错误。
我很困惑。这是我的数据库（删除了三个测试用户的密码）在sql中：
-- phpMyAdmin SQL Dump
-- version 3.5.2.2
-- http://www.phpmyadmin.net
--
-- Host: localhost
-- Generation Time: Feb 15, 2014 at 01:41 PM
-- Server version: 5.1.61
-- PHP Version: 5.2.17
SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
--
-- Database: `u406538221_chat`
--
-- --------------------------------------------------------
--
-- Table structure for table `conversations`
--
CREATE TABLE IF NOT EXISTS `conversations` (
`conversation_id` int(100) NOT NULL AUTO_INCREMENT,
`conversation_subject` varchar(128) COLLATE latin1_general_ci NOT NULL,
PRIMARY KEY (`conversation_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=134 ;
--
-- Dumping data for table `conversations`
--
INSERT INTO `conversations` (`conversation_id`, `conversation_subject`) VALUES
(133, 'haden');
-- --------------------------------------------------------
--
-- Table structure for table `conversations_members`
--
CREATE TABLE IF NOT EXISTS `conversations_members` (
`conversation_id` int(100) NOT NULL,
`user_id` int(100) NOT NULL,
`conversation_last_view` int(10) NOT NULL,
`conversation_deleted` int(1) NOT NULL,
UNIQUE KEY `unique` (`conversation_id`,`user_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci;
--
-- Dumping data for table `conversations_members`
--
INSERT INTO `conversations_members` (`conversation_id`, `user_id`, `conversation_last_view`, `conversation_deleted`) VALUES
(133, 2, 0, 1),
(133, 3, 1392489389, 0);
-- --------------------------------------------------------
--
-- Table structure for table `conversations_messages`
--
CREATE TABLE IF NOT EXISTS `conversations_messages` (
`message_id` int(200) NOT NULL AUTO_INCREMENT,
`conversation_id` int(100) NOT NULL,
`user_id` int(100) NOT NULL,
`message_date` int(10) NOT NULL,
`message_text` text COLLATE latin1_general_ci NOT NULL,
PRIMARY KEY (`message_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=159 ;
--
-- Dumping data for table `conversations_messages`
--
INSERT INTO `conversations_messages` (`message_id`, `conversation_id`, `user_id`, `message_date`, `message_text`) VALUES
(158, 133, 3, 1392489389, 'haden');
-- --------------------------------------------------------
--
-- Table structure for table `users`
--
CREATE TABLE IF NOT EXISTS `users` (
`user_id` int(100) NOT NULL AUTO_INCREMENT,
`user_name` varchar(20) COLLATE latin1_general_ci NOT NULL,
`user_password` varchar(40) COLLATE latin1_general_ci NOT NULL,
PRIMARY KEY (`user_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=5 ;
--
-- Dumping data for table `users`
--
INSERT INTO `users` (`user_id`, `user_name`, `user_password`) VALUES
(1, 'Peter', ''),
(2, 'Haden', ''),
(3, 'Alfie', '');
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
我是一个完全新手，非常困惑，并且一直试图调试这些错误数天但无济于事。
请帮帮我。
提前谢谢。
更新：我被告知需要更多代码，因此这里有private_message.inc.php，带有该功能的页面以及许多其他功能，包括删除功能，可通过init.inc访问任何页面。 php文件：
<?php
// Fetches a summary of the conversations.
function fetch_conversation_summary(){
$sql = "SELECT
`conversations`.`conversation_id`,
`conversations`.`conversation_subject`,
MAX(`conversations_messages`.`message_date`) AS `conversation_last_reply`,
MAX(`conversations_messages`.`message_date`) > `conversations_members`.`conversation_last_view` AS `conversation_unread`
FROM `conversations`
LEFT JOIN `conversations_messages` ON `conversations`.`conversation_id` = `conversations_messages`.`conversation_id`
INNER JOIN `conversations_members` ON `conversations`.`conversation_id` = `conversations_messages`.`conversation_id`
WHERE `conversations_members`.`user_id` = {$_SESSION['user_id']}
AND `conversations_members`.`conversation_deleted` = 0
GROUP BY `conversations`.`conversation_id`
ORDER BY `conversation_last_reply` DESC";
$result = mysql_query($sql);
$conversations = array();
while (($row = mysql_fetch_assoc($result)) !== false){
$conversations[] = array(
'id' => $row['conversation_id'],
'subject' => $row['conversation_subject'],
'last_reply' => $row['conversation_last_reply'],
'unread_messages' => ($row['conversation_unread'] == 1),
);
}
return $conversations;
}
// Fetches all of the messages in the given converstion.
function fetch_conversation_messages($conversation_id){
$conversation_id = (int)$conversation_id;
$sql = "SELECT
`conversations_messages`.`message_date`,
`conversations_messages`.`message_text`,
`users`.`user_name`
FROM `conversations_messages`
INNER JOIN `users` ON `conversations_messages`.`user_id` = `users`.`user_id`
WHERE `conversations_messages`.`conversation_id` = {$conversation_id}
ORDER BY `conversations_messages`.`message_date` DESC";
$result = mysql_query($sql);
var_dump($result);
$messages = array();
while (($row = mysql_fetch_assoc($result)) !== false){
$messages[] = array(
'date' => $row['message_date'],
'unread' => $row['message_unread'],
'text' => $row['message_text'],
'user_name' => $row['user_name'],
);
}
return $messages;
}
// Sets the last view time to the current time for the given conversation.
function update_conversation_last_view($conversation_id){
$conversation_id = (int)$conversation_id;
$time = time() + 18000;
$sql ="UPDATE `conversations_members`
SET `conversation_last_view` = {$time}
WHERE `conversation_id` = {$conversation_id}
AND `user_id` = {$_SESSION['user_id']}";
mysql_query($sql);
}
// Creates a new conversation, making the given users a member.
function create_conversation($user_ids, $subject, $body){
$subject = mysql_real_escape_string(htmlentities($subject));
$body = mysql_real_escape_string(htmlentities($body));
mysql_query("INSERT INTO `conversations` (`conversation_subject`) VALUES ('{$subject}')");
$conversation_id = mysql_insert_id();
$sql = "INSERT INTO `conversations_messages` (`conversation_id`, `user_id`, `message_date`, `message_text`)
VALUES ({$conversation_id}, {$_SESSION['user_id']}, UNIX_TIMESTAMP(), '{$body}')";
mysql_query($sql);
$values = array("({$conversation_id}, {$_SESSION['user_id']}, UNIX_TIMESTAMP(), 0)");
foreach ($user_ids as $user_id){
$user_id = (int)$user_id;
$values[] = "({$conversation_id}, {$user_id}, 0, 0)";
}
$sql = "INSERT INTO `conversations_members` (`conversation_id`, `user_id`, `conversation_last_view`, `conversation_deleted`)
VALUES " . implode(", ", $values);
mysql_query($sql);
}
// Checks to see if the given user is a member of the given conversation.
function validate_conversation_id($conversation_id){
$conversation_id = (int)$conversation_id;
echo 'Conversation ID: '.$conversation_id.'<br />';
echo 'User ID: '.$_SESSION['user_id'].'<br />';
$sql = "SELECT COUNT(1)
FROM `conversations_members`
WHERE `conversation_id` = {$conversation_id}
AND `user_id` = {$_SESSION['user_id']}
AND `conversation_deleted` = 0";
$result = mysql_query($sql);
return (mysql_result($result, 0) == 1);
}
// Adds a message to the given conversation.
function add_conversation_message($conversation_id, $text){
$conversation_id = (int)$conversation_id;
$text = mysql_real_escape_string(htmlentities($text));
$sql = "INSERT INTO `conversations_messages` (`conversation_id`, `user_id`, `message_date`, `message_text`)
VALUES ({$conversation_id}, {$_SESSION['user_id']}, UNIX_TIMESTAMP(), '{$text};')";
mysql_query($sql);
mysql_query("UPDATE `conversations_members` SET `conversation_deleted` = 0 where `conversation_id = {$conversation_id}");
}
// Deletes (or marks as deleted) a given conversation.
function delete_conversation($conversation_id){
$conversation_id = (int)$conversation_id;
$sql = "SELECT DISTINCT `conversation_deleted`
FROM `conversations_members`
WHERE `user_id` != {$_SESSION['user_id']}
AND `conversation_id` = {$conversation_id}";
$result = mysql_query($sql);
//if (mysql_num_rows($result) == 1 && mysql_result($result, 0) == 1){
if (mysql_num_rows($result) == 0){
mysql_query("DELETE FROM `conversations` WHERE `conversation_id` = {$conversation_id}");
mysql_query("DELETE FROM `conversations_members` WHERE `conversation_id` = {$conversation_id}");
mysql_query("DELETE FROM `conversations_messages` WHERE `conversation_id` = {$conversation_id}");
echo 'actually deleting';
}else{
$sql = "UPDATE `conversations_members`
SET `conversation_deleted` = 1
WHERE `conversation_id` = {$conversation_id}
AND `user_id` = {$_SESSION['user_id']}";
mysql_query($sql);
echo 'flagging as deleted';
}
}
?>
最后更新：我已经解决了这个问题：
function fetch_conversation_summary() {
$sql = "SELECT
`conversations`.`conversation_id`,
`conversations`.`conversation_subject`,
MAX(`conversations_messages`.`message_date`) AS `conversation_last_reply`,
MAX(`conversations_messages`.`message_date`) > `conversations_members`.`conversation_last_view` AS `conversation_unread`
FROM `conversations`
LEFT JOIN `conversations_messages` ON `conversations`.`conversation_id` = `conversations_messages`.`conversation_id`
INNER JOIN `conversations_members` ON `conversations`.`conversation_id` = `conversations_members`.`conversation_id`
WHERE `conversations_members`.`user_id` = {$_SESSION['user_id']}
AND `conversations_members`.`conversation_deleted` = 0
GROUP BY `conversations`.`conversation_id`
ORDER BY `conversation_last_reply` DESC";
$result = mysql_query($sql);
$conversations = array();
while (($row = mysql_fetch_assoc($result)) !== false) {
$conversations[] = array(
'id' => $row['conversation_id'],
'subject' => $row['conversation_subject'],
'last_reply' => $row['conversation_last_reply'],
'unread_messages' => ($row['conversation_unread'] == 1),
);
}
return $conversations;
}