Infinite number of Sub-Categories? How?

[Anon]

I have seen programs boasting "Infinite Sub-Categories" for programs such as shopping carts, link indexing, etc.

How do they accomplish this?

One way I have thought about is having the category table with the fields:

id, categoryName, and parentCategory

But, naturally, it would be tough to have the same sub-category names in each category because at about the 3rd level, parentCategory starts referring to more than one record...

Any ideas on how to accomplish "infinite" subcategories?

~Mark

[Anon]

If I use the fields:

id, categoryName, and parentCategory

instead of storing the parentCategory's name, I could store its unique ID.

I don't know why I didn't think about that before...

~Mark

[[deleted]]

The following example is very basic and very inefficient. It does, however, show you the idea behind infinite sub-categories. If you don't understand something just ask and I will reply.

example db:
Table 1 CAT:
cat_id | cat_name

Table 2 SUB:
sub_id | sub_cat_id | sub_cat_name

example code:
$row=mysql_query("select cat_id, cat_name from cat order by cat_name asc");
while ($rs=mysql_fetch_row($row))
{
echo"Category: ".$rs[1]."<br>";
$ct=mysql_fetch_row(mysql_query("select count(*) from sub where sub_cat_id='".$rs[0]."'"));
if ($ct[0]>=1)
{
$row1=mysql_query("select sub_cat_name from sub where sub_cat_id='".$rs[0]."'");
while ($rs1=mysql_fetch_row($row1))
{
echo"Sub-Category: ".$rs1[0]."<br>";
}
}
else
{
echo"no sub categories for this category...<br>";
}
}

[[deleted]]

"because at about the 3rd level, parentCategory starts referring to more than one record..."

If you would allow one child to have many parents yes, but no sane person ever allows that.

the id/parentid structure works perfectly, just remember you'll have to do some recursive functions to get the whole tree to find out where a subcategory belongs.

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[Anon]

My example being:

Computers -> Merchants -> Pennsylvania

Sports -> Merchants -> Florida

Pennsylvania would be a subcat of Merchants, but so would Florida... despite the fact that there is a category called Merchants under Sports as well as Computers.

However, if I were to simply refer to the parentCategory's ID instead of its name, everything is fine... I don't know why I even considered referring to a name.

Then, on each page I could display the items available from that category as well as the categories where parentCategory equals the current page's category.

Simple!

~Mark