Witam,

znalazłem skrypt w necie , ale nie rozumień tu taj powiązań pomiędzy kategorią a podkategorią

tabela i przykładowe dane

[PHP] pobierz, plaintext 
CREATE TABLE `testcat` (
  `id` mediumint(8) unsigned NOT NULL auto_increment,
  `title` varchar(200) NOT NULL,
  `left_id` int(10) NOT NULL,
  `right_id` int(10) NOT NULL,
  `level` mediumint(8) unsigned NOT NULL,
  UNIQUE KEY `id` (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=14 ;
 
-- 
-- Dumping data for table `testcat`
-- 
 
INSERT INTO `testcat` VALUES (1, 'Digital Art', 9, 20, 1);
INSERT INTO `testcat` VALUES (2, '3D Art', 10, 11, 2);
INSERT INTO `testcat` VALUES (3, 'Drawings', 12, 13, 2);
INSERT INTO `testcat` VALUES (4, 'Miscellaneous', 14, 15, 2);
INSERT INTO `testcat` VALUES (5, 'Photo Manipulation', 16, 17, 2);
INSERT INTO `testcat` VALUES (6, 'Wallpapers', 18, 19, 2);
INSERT INTO `testcat` VALUES (7, 'Internet Use', 20, 25, 2);
INSERT INTO `testcat` VALUES (8, 'Signatures', 21, 22, 3);
INSERT INTO `testcat` VALUES (9, 'Avatars', 23, 24, 3);
INSERT INTO `testcat` VALUES (10, 'Photography', 1, 8, 1);
INSERT INTO `testcat` VALUES (11, 'Landscape', 6, 7, 2);
INSERT INTO `testcat` VALUES (12, 'Portrait', 4, 5, 2);
INSERT INTO `testcat` VALUES (13, 'Architecture', 2, 3, 2);
[PHP] pobierz, plaintext 

i skrypt

[PHP] pobierz, plaintext 
<?php 
$sql = 'SELECT id, left_id, right_id, level, title FROM testcat ORDER BY left_id asc'; 
$result = mysql_query($sql) or die(mysql_error());  
$level = 1;  
$classes = array('cat' => array(1 => 'maincat', 'subcat'), 'element' => array(1 => 'sub', 'subcatsub'));  
$first = false;  
 
print '<select class="select" name="id">' . "\n";  
while($row = mysql_fetch_assoc($result))  
{  
    while($level > $row['level'])  
    {  
        $level--;  
        print str_repeat("\t", $level) . '</optgroup>' . "\n";  
    }  
    if(has_children($row['left_id'], $row['right_id']))  
    {  
        print str_repeat("\t", $row['level']) . '<optgroup class="' . $classes['cat'][$row['level']] . '" label="' . $row['title'] . '">' . "\n";  
        $level++;  
        $first = true;  
        continue;  
    }  
    print str_repeat("\t", $row['level']) . '<option class="' . $classes['element'][$row['level']] . (($first) ? ' first' : '') . '" value="' . $row['id'] . '">' . $row['title'] . '</option>' . "\n";  
    $first = false;  
}  
while($level > 1)  
{  
    $level--;  
    print str_repeat("\t", $level) . '</optgroup>' . "\n";  
}  
 
print '</select>' . "<br />\n";  
 
function has_children($left_id, $right_id)  
{ // MPTT is good!  
    return (bool) ( ($right_id - $left_id - 1) / 2 );  
}  <?php 
$sql = 'SELECT id, left_id, right_id, level, title FROM testcat ORDER BY left_id asc'; 
$result = mysql_query($sql) or die(mysql_error());  
$level = 1;  
$classes = array('cat' => array(1 => 'maincat', 'subcat'), 'element' => array(1 => 'sub', 'subcatsub'));  
$first = false;  
 
print '<select class="select" name="id">' . "\n";  
while($row = mysql_fetch_assoc($result))  
{  
    while($level > $row['level'])  
    {  
        $level--;  
        print str_repeat("\t", $level) . '</optgroup>' . "\n";  
    }  
    if(has_children($row['left_id'], $row['right_id']))  
    {  
        print str_repeat("\t", $row['level']) . '<optgroup class="' . $classes['cat'][$row['level']] . '" label="' . $row['title'] . '">' . "\n";  
        $level++;  
        $first = true;  
        continue;  
    }  
    print str_repeat("\t", $row['level']) . '<option class="' . $classes['element'][$row['level']] . (($first) ? ' first' : '') . '" value="' . $row['id'] . '">' . $row['title'] . '</option>' . "\n";  
    $first = false;  
}  
while($level > 1)  
{  
    $level--;  
    print str_repeat("\t", $level) . '</optgroup>' . "\n";  
}  
 
print '</select>' . "<br />\n";  
 
function has_children($left_id, $right_id)  
{ // MPTT is good!  
    return (bool) ( ($right_id - $left_id - 1) / 2 );  
}  
[PHP] pobierz, plaintext 

http://en.wikipedia.org/wiki/Nested_set_model