This is the correct structure for this:
Code:
DROP TABLE IF EXISTS `categories`;
CREATE TABLE IF NOT EXISTS `categories` (
`categories_id` int(11) NOT NULL auto_increment,
`categories_image` varchar(64) default NULL,
`parent_id` int(11) NOT NULL default '0',
`sort_order` int(3) default NULL,
`date_added` datetime default NULL,
`last_modified` datetime default NULL,
`categories_status` tinyint(1) NOT NULL default '1',
PRIMARY KEY (`categories_id`),
KEY `idx_parent_id_cat_id_zen` (`parent_id`,`categories_id`),
KEY `idx_status_zen` (`categories_status`),
KEY `idx_sort_order_zen` (`sort_order`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=68 ;
--
-- Dumping data for table `categories`
--
INSERT INTO `categories` (`categories_id`, `categories_image`, `parent_id`, `sort_order`, `date_added`, `last_modified`, `categories_status`) VALUES
(1, 'categories/category_hardware.gif', 0, 1, '2003-12-23 03:18:19', '2004-05-21 00:32:17', 1),
(2, 'categories/category_software.gif', 0, 2, '2003-12-23 03:18:19', '2004-05-22 21:14:57', 1),