PHP recursive function to retrieve all children of a category

Question

Hello guys,

I would like to write a recursive PHP function to retrive all the children for the specified category. I tried the one described here but it didn't output what I have expected.

My categories table looks like this:

CREATE TABLE `categories` (
 `category_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
 `category_name` varchar(256) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
 `category_slug` varchar(256) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
 `category_parent` smallint(5) unsigned NOT NULL DEFAULT '0',
 `category_description_ro` text CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
 `category_description_en` text CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
 PRIMARY KEY (`category_id`)
) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=latin1

Bellow is an example of data in the table:

category id | category name | category_parent

1            Categoria 1            0        
2            Categoria 2            0        
3            Categoria 3            0        
4            Categoria 1.1          1        
5            Categoria 1.2          1        
6            Categoria 1.3          1        
7            Categoria 1.1.2        4 

Thanks.

Answer 1

function get_categories($parent = 0)
{
    $html = '<ul>';
    $query = mysql_query("SELECT * FROM `categories` WHERE `category_parent` = '$parent'");
    while($row = mysql_fetch_assoc($query))
    {
        $current_id = $row['category_id'];
        $html .= '<li>' . $row['category_name'];
        $has_sub = NULL;
        $has_sub = mysql_num_rows(mysql_query("SELECT COUNT(`category_parent`) FROM `categories` WHERE `category_parent` = '$current_id'"));
        if($has_sub)
        {
            $html .= get_categories($current_id);
        }
        $html .= '</li>';
    }
    $html .= '</ul>';
    return $html;
}

print get_categories();