Need your opinion on this recursive function

[kensai]

Hi. I've a recursive function to retrieve categories from database. The function itself work just fine I'm stuck with something. I want to display sub categories more inline. The more sub it is, more inline it should display. Here's my PHP code:

function write_sub_category($id){

$sql="select rel.kat_id_1,kat.name 
		from categories as kat
		inner join kat_rel as rel
		on kat.id=rel.kat_id_1
		where kat_id_2=".$id;

$query=mysql_query($sql);
$row_count=mysql_num_rows($query);

if($row_count>0){

	while($row=mysql_fetch_array($query)){

		$tmpid=$row["kat_id_1"];

		echo "<br>»".$row["name"]."<br>\n\r";

		write_sub_category($tmpid);

	}
}
}

-------------------------
And here's the output:
-------------------------

»sub cat 1

»sub cat 1 sub 1

»sub cat 1 sub 1 sub 1

»sub cat 1 sub 2

---------------------
What I want is this:
---------------------

»sub cat 1

»»sub cat 1 sub 1

»»»sub cat 1 sub 1 sub 1

»»sub cat 1 sub 2

What should I do for this? Can you give me an idea?

[adamgeorge]

Well, just so you know, mysql_query returns a result identifier on a successful query - basically some sort of link connection thingy with the database.

So your choice of variable names in your code are prolly not the best. Try this:

$result =mysql_query($sql);

if($result)
   $row_count=mysql_num_rows($result);
else
   return false;

Notice how I check to see if mysql_query returned a valid result before using mysql_num_rows. If you don't mysql_num_rows will through an error if the result is invalid.

Anyway, onto your question. Try using tables. Maybe something like this:

function write_sub_category($id){

$sql="select rel.kat_id_1,kat.name 
        from categories as kat
        inner join kat_rel as rel
        on kat.id=rel.kat_id_1
        where kat_id_2=".$id;

$result=mysql_query($sql);

if($result)
   $row_count=mysql_num_rows($result);
else
    return;

if($row_count>0){
    echo "<table cellspacing=0 cellpadding=0 border=0><tr><td style='padding-left:15px;'>";

    while($row=mysql_fetch_array($query)){

        $tmpid=$row["kat_id_1"];
        echo "»".$row["name"];

        write_sub_category($tmpid);
    }
    echo "</td></tr></table>";
}
}

something like that anyway... Just depends what you want to do. Maybe the table needs to be printed in each iteration of the while loop. I can't really tell, as I'm not sure what you're doing. You'll know though. Do you really need those >> at the start? If you do, instead of

 if($result)
       $row_count=mysql_num_rows($result);
    else
        return;

do

 if($result)
       $row_count=mysql_num_rows($result);
    else
        ">>";

and then just print it out when the function returns. you follow?

cya man.
-Adam 🙂

[barand]

I've achieved the result you want by tracking the recursion depth

define as

function write_sub_category($id, $depth)

and increment the depth with each call.

The depth then tells you how far to indent eac time

hth