用户“类别”表作为“子类别”的标题

Question

I don't know if this is possible at all... But I need to create an sql query that lists all my Categories with their Sub Categories. Problem is that Categories and Sub Categories are stored in separate tables.

The database structure is as follows: TABLE NAME: "Categories", COLUMNS: "ID, Name"

TABLE NAME: "Sub_Categories". COLUMNS: "ID, Name, Category_ID". The category_ID is used to link each sub category to it's parent category using ID's.

Right now I just have an sql query code that pulls all the "Categories"... how can I make it so that it will show a list of sub categories under each one?

<?php
$catlist= mysql_query('SELECT * FROM categories WHERE hide = 0 ORDER BY `order` ASC')
or die(mysql_error());  
?>
<?php foreach ($catlist as $catitem): ?>
<h2 class="category"><?php echo $catitem['name']; ?></h2>
<?php endforeach; ?>
<?php ?>

Answer 1

this will get you the rest of the info - you will then need to do layout and suppress the repeating category text.

SELECT * 
FROM categories c, sub_categories s
WHERE c.hide = 0 
AND s.category_id = c.category_id
ORDER BY `order` ASC

Answer 2

You could use a join onto the subcategories table. http://dev.mysql.com/doc/refman/5.0/en/join.html

However, I recommend not differentiating between top level and sub-level categories at the table level, but rather put them all in one table with the following fields: parent_id, left_id, and right_id. Basically, this allows an unlimited depth of categories within a hierarchy. It may take a little research into how to properly implement it, but it is more powerful by far.