PHP + SQL - Group By Parent ID - php

Question

I have a permissions table:
| id | name | Other stuff | parent_id
| 1 | name1 | ... | 3
| 2 | name2 | ... | 3
| 3 | groupName1| ... | null
Inside the permissions table i have the permissions themsleves, which are the ones that do have parent_id, i also have the groups (parents) which do not have parent_id because they are the parents.
So let's say i want to organize the groups in 'li' tags and inside those i want to list all the permissions that belong to that group.
I need the SQL that shows all the group names, and foreach group show the permissions. I assume that requires a couple of 'joins', (i'm kinda of a noob in sql).
Thanks in advance.
EDIT
Here's the current result: open this
See where it says 'Ver' , 'Opção 3' and 'ADMIN' , they are aligned, i wish the same result to both colums above those ('listagem' and 'manutenções').
Here's my current code for reference:
<li class="dropdown dropdown-large">
MENU <b class="caret"></b>
<ul class="dropdown-menu dropdown-menu-large row">
<?php
$campos = DB::table('permissions as permission')
->select('permission.name as Grupo' , 'p.id' , 'p.name', 'p.parent_id', 'p.url')
->join('permissions as p','permission.id','=','p.parent_id')
->orderBy('permission.name')
->distinct()->get();
$nomeAntigo = null;
foreach($campos as $campo) {
$data = (array) $campo;
//SO METE AS PERMISSOES QUE O TIPO DE PERFIL PERMITE
if (Auth::user()->can($data['name'])){
if($nomeAntigo !== $data['Grupo']) {
$nomeAntigo = $data['Grupo'];
echo '<li class="col-sm-3">';
echo '<ul>';
echo ' <li class="dropdown-header"><b>'.$data['Grupo'].'</b></li>';
echo '</ul>';
echo '</li>';
}
echo '<li>'.$data['name'].'</li>';
}
}
?>
</ul>
</li>

Answer 1

there are different solutions.
1) use multiple querys (prepared statements would be perfect). First query returns the groups. For each group query again against the database to return the permissions for each group.
$prep = $pdo->prepare("SELECT id, name FROM permissions WHERE parant_id=?");
foreach($pdo->query("SELECT name FROM permissions WHERE parent_id IS NULL") as $row) {
$r = $prep->execute([$row['id']]);
// loop through it and echo
}
2) I'm not sure what's the correct name for the following is in english. In German it's "Gruppenbruch". Translated into englisch it's something like "control break". (if anybody knows the correct name, please edit or leave a comment)
SELECT pg.name as groupName, p.id, p.name, p.parent_id FROM permissions as pg
INNER JOIN permissions as p ON pg.id = p.parent_id
ORDER BY pg.name, p.name
Here's a working sqlfiddle for the query: http://sqlfiddle.com/#!9/e8fda1/2
now you can do something like
$resultset = $pdo->query(QUERY_FROM_ABOVE); // pdo
$oldGroupName = null;
foreach($resultset as $record) {
if($oldGroupName != $record['groupName']) {
if($oldGroupName != null) echo "</ul>";
echo "<h1>".htmlentities($record['groupName'])."</h1>";
echo "<ul>";
}
echo "<li>".$record['name']."</li>";
}
echo "</ul>";