PHP MySQL array error [closed] - php

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I am having trouble with a function for a PHP/MySQL instant messaging system. A variable ($sql) is defined as a MySQL query, which is then queried, and returns a resource ID. However, the following while statement returns 'Array' instead of its supposed contents.
<?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;
$sql = "SELECT
`conversations_messages`.`message_date`,
`conversations_messages`.`message_date` > `conversations_members`.`conversation_last_view` AS `message_unread`,
`conversations_messages`.`message_text`,
`users`.`user_name`
FROM `conversations_messages`
INNER JOIN `users` ON `conversations_messages`.`user_id` = `users`.`user_id`
INNER JOIN `conversations_members` ON `conversations_messages`.`conversation_id` = `conversations_members`.`conversation_id`
WHERE `conversations_messages`.`conversation_id` = {$conversation_id}
AND `conversations_members`.`user_id` = {$_SESSION['user_id']}
ORDER BY `conversations_messages`.`message_date` DESC";
$result = mysql_query($sql);
echo $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'],
);
}
var_dump( $messages );
}
// Sets the last view time to the current time for the given conversation.
function update_conversation_last_view($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;
$values = array("({$conversation_id}, {$_SESSION['user_id']}, UNIX_TIMESTAMP(), 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;
$sql = "SELECT COUNT(1)
FROM `conversations_members`
WHERE `conversation_id` = {$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}");
}else{
$sql = "UPDATE `conversations_members`
SET `conversation_deleted` = 1
WHERE `conversation_id` = {$conversation_id}
AND `user_id` = {$_SESSION['user_id']}";
mysql_query($sql);
}
}
?>
I have tried echoing the error, $messages (as you can see from the code). In addition, I have echoed the result of the SQL query.
Update: I did the mentioned var_dump and my result was:
Resource id #16array(0) { } Array ( )

Answer 1

Sure it prints Array because that is what $messages is. If you want to print the contents of $messages you can use var_dump or print_r.
Similar reason for $result. $result is a resource type (at least as long as the query is successful). Printing it does not make sense since it is an internal reference. You have to pass it to a function like mysql_fetch_assoc or mysql_fetch_array or similar that can process such a resource.
Regarding your updated question: This output tells you that your array is empty and does not contain any elements. Are you sure your SQL-Query returns any rows?