Too many queries, php. Creating lite forum engine - php

Question

I've started to writing my engine of forum, just to refresh php skills.
My problem is that, when I make a board and one theard, I have double queries.
I know why, I have "foreach in different foreach" but I cannot find a way to sort it out, can you guys help me how would you do it? To avoid this big number of queries?
An example, SMF forum main page has only 12 queries (NO MATTER OF NUMBERS BOARDS AND THEARDS).
My page have 12 already, but I have only 2 categories, 5 boards, 4 theards, 1 user.
If I add one board, and one theard I have +2 queries.
<?php
if(!defined('USED'))
exit;
# Name of page!
$page = 'Forum';
$db = new Database();
$array = $db -> select("SELECT `id`,`name` FROM `".PREFIX."category`");
if(count($array) > 0)
{
$container .= '';
foreach($array as $category)
{
$container .= '<div class="panel panel-primary" id="category-'.$category['id'].'">
<div class="panel-heading">
<h3 class="panel-title">
'.$category['name'].'
</h3>
</div>
<table class="table table-bordered table-striped table-hover">
<thead>
<tr>
<th class="col-md-9">Board Name</th>
<th class="col-md-3">Latest</th>
</tr>
</thead>';
$array2 = $db -> select("SELECT `id`,`id_category`,`name`,`info` FROM `".PREFIX."boards` WHERE `id_category`=".$category['id']."");
if(count($array2) > 0)
{
foreach($array2 as $board)
{
$container .='<tbody>
<tr>
<td>
<strong>'.$board['name'].'</strong><br/>
<small>'.$board['info'].'</small>
</td>';
$array3 = $db -> select("SELECT `id`,`id_board`,`title`,`created_by`,`created_date` FROM `".PREFIX."theards` WHERE `id_board`=".$board['id']." ORDER BY `created_date` DESC LIMIT 1");
if(count($array3) > 0)
{
foreach($array3 as $theards)
{
$array4 = $db -> select("SELECT `id`,`name` FROM `".PREFIX."users` WHERE `id`=".$theards['created_by']."");
foreach($array4 as $user)
{
$created_by = $user['name'];
}
$container .='<td>
'.$theards['title'].'<br/><small>'.$created_by.', <abbr class="timeago" title="'.$theards['created_date'].'">less than a month ago</abbr></small>
</td>';
}
}
else
{
$container .= '<td>
Nothing is here!
</td>';
}
$container .=' </tr>
</tbody>';
}
}
else
{
$container .='<tbody>
<tr>
<td>Nothing is here!</td>
<td>...</td>
</tr>
</tbody>';
}
$container .='</table>
</div>';
}
}
else
{
Site::Error("You need to add a category first!");
}
And my select:
public function select($query) {
$rows = array();
$result = $this -> query($query);
if($result === false) {
return false;
}
while ($row = $result -> fetch_assoc()) {
$rows[] = $row;
}
global $db_count;
$db_count = !isset($db_count) ? 1 : $db_count + 1;
return $rows;
}
Ive added $db_count at the end of the file to check numbers of queries.

Answer 1

Instead of running one query to get a list of IDs, then looping across those IDs to get another set of IDS, then looping across those IDs to get a set of data, how about writing one query, using a JOIN to line up the three tables?