创建表
CREATE TABLE IF NOT EXISTS `categories` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(37) COLLATE utf8_unicode_ci NOT NULL,
`parentid` int(11) DEFAULT '0',
PRIMARY KEY (`id`),
UNIQUE KEY `id` (`id`),
KEY `parentid_fk` (`parentid`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1;
INSERT INTO `categories` (`id`, `name`, `parentid`) VALUES
(1, 'animal', 0),
(2, 'vegetable', 0),
(3, 'mineral', 0),
(4, 'doggie', 1),
(5, 'kittie', 1),
(6, 'horsie', 1),
(7, 'gerbil', 0),
(8, 'birdie', 1),
(9, 'carrot', 2),
(10, 'tomato', 2),
(11, 'potato', 2),
(12, 'celery', 2),
(13, 'rutabaga', 2),
(14, 'quartz', 3),
(15, 'feldspar', 3),
(16, 'silica', 3),
(17, 'gypsum', 3),
(18, 'hunting', 4),
(19, 'companion', 4),
(20, 'herding', 4),
(21, 'setter', 18),
(22, 'terrier', 18),
(23, 'poodle', 19),
(24, 'chihuahua', 19),
(25, 'shepherd', 20),
(26, 'collie', 20);
php代码
// $current_cat_id: the current category id number
// $count: just a counter, call it as 0 in your function call and forget about it
/* GET THE DROP DOWN LIST OF CATEGORIES */
function get_cat_selectlist($current_cat_id, $count, $lastname='') {
static $option_results;
// if there is no current category id set, start off at the top level (zero)
if (!isset($current_cat_id)) {
$current_cat_id=1;
}
// increment the counter by 1
$count = $count+1;
// query the database for the sub-categories of whatever the parent category is
$sql = "SELECT id, name from categories where parentid = ".$current_cat_id." order by name asc";
$get_options = mysql_query($sql);
$num_options = mysql_num_rows($get_options);
// our category is apparently valid, so go ahead €¦
if ($num_options > 0) {
while (list($cat_id, $cat_name) = mysql_fetch_row($get_options)) {
// if its not a top-level category, indent it to
//show that its a child category
if ($current_cat_id!=0) {
$indent_flag = $lastname . '--';
// for ($x=2; $x<=$count; $x++) {
$indent_flag .= '>';
// }
}
$cat_name = $indent_flag.$cat_name;
$option_results[$cat_id] = $cat_name;
// now call the function again, to recurse through the child categories
get_cat_selectlist($cat_id, $count, $cat_name);
}
}
return $option_results;
}
echo '<select name="cat_id">';
echo '<option value="">-- Select -- </option>';
$get_options = get_cat_selectlist(0, 0);
if (count($get_options) > 0){
$categories = $_POST['cat_id'];
foreach ($get_options as $key => $value) {
$options .="<option value=\"$key\"";
// show the selected items as selected in the listbox
if ($_POST['cat_id'] == "$key") {
$options .=" selected=\"selected\"";
}
$options .=">$value</option>\n";
}
}
echo $options;
echo '</select>';
输出将是
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