building a forum...need a bit of help.

jonaHill87 · November 15, 2008

Hi all. I'm building a small forum and it's almost finished but there's one thing I didn't take into consideration. I don't even know if this is possible the way I have my db set up so I will provide as much info as I can here.

What I'm trying to do:

I didn't consider how I want my index posts to be ordered. I want them to be ordered by date(whether its a new topic or a reply to a topic) so that the latest posting is the first index. (basically like any forum). Now I have no idea how to do this because I have a 'topics' db table and 'replies' db table that both have a date field and I need to compare those dates. But if there are no replies for a topic, I can't compare the dates.

Here's a stripped down version of my db tables:

Topics:

Field: topicId PK

Field: title

Field: memberId FK

Field: comment

Field: date/time

Replies:

Field: replyId PK

Field: topicId FK

Field: memberId FK

Field: comment

Field: date/time

So I can't figure out how this can be done with a single query or even multiple queries on both tables. Any help would be greatly appreciated as I'm about ready to give up.

ShiloVir · November 15, 2008

Heres a sample Forum. Modify to Fit your needs:

SQL Query:

CREATE TABLE forum_topics (
topic_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
topic_title VARCHAR (150),
topic_create_time DATETIME,
topic_owner VARCHAR (150)
};

CREATE TABLE forum_posts (
post_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
topic_id INT NOT NULL,
post_text TEXT,
post_create_time DATETIME,
post_owner VARCHAR (150)
);

Addtopic.html

<html>
<head>
<title>Add a Topic</title>
</head>
<body>
<h1>Add a Topic</h1>
<form method="post" action="do_addtopic.php">
<p><strong>Your E-Mail Address:</strong><br/>
<input type="text" name="topic_owner" size="40" maxlength="150"/></p>
<p><strong>Topic Title:</strong><br/>
<input type="text" name="topic_title" size="40" maxlength="150"/></p>
<p><strong>Post Text:</strong><br/>
<textarea name="post_text" rows="8" cols="40" wrap="virtual"></textarea></p>
<p><input type="submit" name="submit" value="Add Topic"></p>
</form>
</body>
</html>

do_addtopic.php

<?php
//check for required fields from the form
if ((!$_POST["topic_owner"]) || (!$_POST["topic_title"]) || (!$_POST["post_text"])) {
header("Location: addtopic.html");
exit;
}

//connect to server
$mysqli = mysqli_connect("localhost", "joeuser", "somepass", "testDB");

//create and issue the first query
$add_topic_sql = "INSERT INTO forum_topics (topic_title, topic_create_time,topic_owner) VALUES ('".$_POST["topic_title"]."',now(), '".$_POST["topic_owner"]."')";
$add_topic_res = mysqli_query($mysqli, $add_topic_sql) or die(mysqli_error($mysqli));

//get the id of the last query
$topic_id = mysqli_insert_id($mysqli);

//create and issue the second query
$add_post_sql = "INSERT INTO forum_posts (topic_id,post_text,post_create_time,post_owner) VALUES ('".$topic_id."', '".$_POST["post_text"]."', now(), '".$_POST["topic_owner"]."')";
$add_post_res = mysqli_query($mysqli, $add_post_sql) or die(mysqli_error($mysqli));

//close connection to MySQL
mysqli_close($mysqli);

//create nice message for user
$display_block = "<P>The <strong>".$_POST["topic_title"]."</strong> topic has been created.</p>";
?>
<html>
<head>
<title>New Topic Added</title>
</head>
<body>
<h1>New Topic Added</h1>
<?php echo $display_block; ?>
</body>
</html>

replytopost.php

<?php
//connect to server
$mysqli = mysqli_connect("localhost", "joeuser", "somepass", "testDB");

//check to see if we're showing the form or adding the post
if (!$_POST) {
// showing the form; check for required item in query string
if (!isset($_GET["post_id"])) {
	header("Location: topiclist.php");
	exit;
}

//still have to verify topic and post
$verify_sql = "SELECT ft.topic_id, ft.topic_title FROM forum_posts AS fp LEFT JOIN forum_topics AS ft ON fp.topic_id = ft.topic_id WHERE fp.post_id = '".$_GET["post_id"]."'";

$verify_res = mysqli_query($mysqli, $verify_sql) or die(mysqli_error($mysqli));

if (mysqli_num_rows($verify_res) < 1) {
	//this post or topic does not exist
	header("Location: topiclist.php");
	exit;
} else {
	//get the topic id and title
	while($topic_info = mysqli_fetch_array($verify_res)) {
		$topic_id = $topic_info['topic_id'];
		$topic_title = stripslashes($topic_info['topic_title']);
	}

	echo "
	<html>
	<head>
	<title>Post Your Reply in ".$topic_title."</title>
	</head>
	<body>
	<h1>Post Your Reply in $topic_title</h1>
	<form method=\"post\" action=\"".$_SERVER["PHP_SELF"]."\">
	<p><strong>Your E-Mail Address:</strong><br/>
	<input type=\"text\" name=\"post_owner\" size=\"40\" maxlength=\"150\"></p>

	<p><strong>Post Text:</strong><br/>
	<textarea name=\"post_text\" rows=\"8\" cols=\"40\" wrap=\"virtual\"></textarea>

	<input type=\"hidden\" name=\"topic_id\" value=\"$topic_id\">
	<P><input type=\"submit\" name=\"submit\" value=\"Add Post\"></p>

	</form>
	</body>
	</html>";
}

//free result
mysqli_free_result($verify_res);

//close connection to MySQL
mysqli_close($mysqli);

} else if ($_POST) {
//check for required items from form
if ((!$_POST["topic_id"]) || (!$_POST["post_text"]) || (!$_POST["post_owner"])) {
	header("Location: topiclist.php");
	exit;
}

//add the post
$add_post_sql = "INSERT INTO forum_posts (topic_id,post_text,post_create_time,post_owner) VALUES ('".$_POST["topic_id"]."', '".$_POST["post_text"]."', now(), '".$_POST["post_owner"]."')";
$add_post_res = mysqli_query($mysqli, $add_post_sql) or die(mysqli_error($mysqli));

//close connection to MySQL
mysqli_close($mysqli);

//redirect user to topic
header("Location: showtopic.php?topic_id=".$_POST["topic_id"]);
exit;
}
?>

showtopic.php

<?php
//check for required info from the query string
if (!isset($_GET["topic_id"])) {
header("Location: topiclist.php");
exit;
}

//connect to server
$mysqli = mysqli_connect("localhost", "joeuser", "somepass", "testDB");

//verify the topic exists
$verify_topic_sql = "SELECT topic_title FROM forum_topics WHERE topic_id = '".$_GET["topic_id"]."'";
$verify_topic_res =  mysqli_query($mysqli, $verify_topic_sql) or die(mysqli_error($mysqli));

if (mysqli_num_rows($verify_topic_res) < 1) {
//this topic does not exist
$display_block = "<p><em>You have selected an invalid topic.<br/>
Please <a href=\"topiclist.php\">try again</a>.</em></p>";
} else {
//get the topic title
while ($topic_info = mysqli_fetch_array($verify_topic_res)) {
	$topic_title = stripslashes($topic_info['topic_title']);
}

//gather the posts
$get_posts_sql = "SELECT post_id, post_text, DATE_FORMAT(post_create_time, '%b %e %Y at %r') AS fmt_post_create_time, post_owner FROM forum_posts WHERE topic_id = '".$_GET["topic_id"]."' ORDER BY post_create_time ASC";
$get_posts_res = mysqli_query($mysqli, $get_posts_sql) or die(mysqli_error($mysqli));

//create the display string
$display_block = "
<p>Showing posts for the <strong>".$topic_title."</strong> topic:</p>
<table width=\"100%\" cellpadding=\"3\" cellspacing=\"1\" border=\"1\">
<tr>
<th>AUTHOR</th>
<th>POST</th>
</tr>";

while ($posts_info = mysqli_fetch_array($get_posts_res)) {
	$post_id = $posts_info['post_id'];
	$post_text = nl2br(stripslashes($posts_info['post_text']));
	$post_create_time = $posts_info['fmt_post_create_time'];
	$post_owner = stripslashes($posts_info['post_owner']);

	//add to display
 	$display_block .= "
	<tr>
	<td width=\"35%\" valign=\"top\">".$post_owner."<br/>[".$post_create_time."]</td>
	<td width=\"65%\" valign=\"top\">".$post_text."<br/><br/>
	<a href=\"replytopost.php?post_id=".$post_id."\"><strong>REPLY TO POST</strong></a></td>
	</tr>";
}

//free results
mysqli_free_result($get_posts_res);
mysqli_free_result($verify_topic_res);

//close connection to MySQL
mysqli_close($mysqli);

//close up the table
$display_block .= "</table>";
}
?>
<html>
<head>
<title>Posts in Topic</title>
</head>
<body>
<h1>Posts in Topic</h1>
<?php echo $display_block; ?>
</body>
</html>

topiclist.php

<?php
//connect to server
$mysqli = mysqli_connect("localhost", "joeuser", "somepass", "testDB");

//gather the topics
$get_topics_sql = "SELECT topic_id, topic_title, DATE_FORMAT(topic_create_time,  '%b %e %Y at %r') aS fmt_topic_create_time, topic_owner FROM forum_topics ORDER BY topic_create_time DESC";
$get_topics_res = mysqli_query($mysqli, $get_topics_sql) or die(mysqli_error($mysqli));

if (mysqli_num_rows($get_topics_res) < 1) {
//there are no topics, so say so
$display_block = "<p><em>No topics exist.</em></p>";
} else {
//create the display string
$display_block = "
<table cellpadding=\"3\" cellspacing=\"1\" border=\"1\">
<tr>
<th>TOPIC TITLE</th>
<th># of POSTS</th>
</tr>";

while ($topic_info = mysqli_fetch_array($get_topics_res)) {
	$topic_id = $topic_info['topic_id'];
	$topic_title = stripslashes($topic_info['topic_title']);
	$topic_create_time = $topic_info['fmt_topic_create_time'];
	$topic_owner = stripslashes($topic_info['topic_owner']);

	//get number of posts
	$get_num_posts_sql = "SELECT COUNT(post_id) AS post_count FROM forum_posts WHERE topic_id = '".$topic_id."'";
	$get_num_posts_res = mysqli_query($mysqli, $get_num_posts_sql) or die(mysqli_error($mysqli));

	while ($posts_info = mysqli_fetch_array($get_num_posts_res)) {
		$num_posts = $posts_info['post_count'];
	}

	//add to display
	$display_block .= "
	<tr>
	<td><a href=\"showtopic.php?topic_id=".$topic_id."\"><strong>".$topic_title."</strong></a><br/>
	Created on ".$topic_create_time." by ".$topic_owner."</td>
	<td align=center>".$num_posts."</td>
	</tr>";
}
//free results
mysqli_free_result($get_topics_res);
mysqli_free_result($get_num_posts_res);

//close connection to MySQL
mysqli_close($mysqli);

//close up the table
$display_block .= "</table>";
}
?>
<html>
<head>
<title>Topics in My Forum</title>
</head>
<body>
<h1>Topics in My Forum</h1>
<?php echo $display_block; ?>
<p>Would you like to <a href="addtopic.html">add a topic</a>?</p>
</body>
</html>

Of course this isnt secure and shouldnt be trusted to work on. u will need to add some security features and add some sort of login system.

jonaHill87 · November 15, 2008

Whoa, that a lot of code. Ok thanks I'll go through this all of this and post back if I have any problems. btw, what's 'mysqli'? I haven't seen that before.

ShiloVir · November 15, 2008

Whoa, that a lot of code. Ok thanks I'll go through this all of this and post back if I have any problems. btw, what's 'mysqli'? I haven't seen that before.

PHP.NET - MySQLi

Yah. I made a few Edits with the SQL Query. So if u get any problems drop your database and resend the SQL query. if ur still getting a problem. then post back :-\

PS: Dont drop ur database if theres other stuff on it. I suggest making a new database to try this code out

jonaHill87 · November 15, 2008

alright. thanks bud

jonaHill87 · December 3, 2008

Sorry it took me so long to report back but I've been busy. Anyway, thanks for sharing these pages but they do not

solve my problem. I want to order my topics from newest to oldest (by post date) so that when some one posts inside of a topic, that topic will be at the top of the topic list. I changed my database to the database you provided above because it's easier to work with then my original db.

The closest I have come to figuring this out is with this query but it will only pick up the first entry of the topic_id and skip later post entries. I cant get it to pick only the latest post date for that topic_id. I hope that makes sense.

select distinct t.topic_id, t.topic_title

from forum_posts p, forum_topics t

where p.topic_id = t.topic_id

order by p.post_create_time desc

premiso · December 3, 2008

select t.topic_id, t.topic_title, p.post_id
from forum_posts p, forum_topics t
where p.topic_id = t.topic_id
order by p.post_create_time desc

That should pick up the topics. You were limiting yourself by not including the post_id and using the distinct.

That would return x rows depending on how many posts there are for a topic so you can show all the posts by the id.

Hope that helps.

jonaHill87 · December 4, 2008

You're right I do need the post_id as well, but, the reason I tried using distinct is because I don't want the same topic_id to be displayed more than once. Let me see if I can explain this a bit better. I have 5 records(topics) in my forum_topics table and I have 8 records(posts) in my forum_posts table. So obviously one of my topics has more than 1 post. In my query, I want to display only the 5 records(topics) with each containing the post_id of the newest post(post_create_time). Your query gives me all 8 records. I'm beginning to think this is impossible. Any more help would be greatly appreciated.

jonaHill87 · December 5, 2008

bump. any ideas anyone?

gevans · December 5, 2008

select t.topic_id, t.topic_title, p.post_id
from forum_posts p, forum_topics t
where p.topic_id = t.topic_id
order by p.post_create_time desc
limit 5

I didn't read everything, but from what I can see you just want to limit your query

jonaHill87 · December 7, 2008

no dice man. gives me the same results as previous but limits to 5 records.

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