php category function

Hi I am using following php code for showing categories in my site (found it online)

//Categories
$nav_query = $mysql->query("SELECT * FROM categories WHERE sub = 0 ORDER BY id");
$categories = "";					// Clear the directory tree
$depth = 1;					// Child level depth.
$top_level_on = 1;			// What top-level category are we on?
$exclude = array();			// Define the exclusion array
array_push($exclude, 0);	// Put a starting value in it
 
while ( $nav_row = $mysql->fetch_array($nav_query) )
{
	$goOn = 1;			// Resets variable to allow us to continue building out the tree.
	for($x = 0; $x < count($exclude); $x++ )		// Check to see if the new item has been used
	{
		if ( $exclude[$x] == $nav_row['id'] )
		{
			$goOn = 0;
			break;				// Stop looking b/c we already found that it's in the exclusion list and we can't continue to process this node
		}
	}
	if ( $goOn == 1 )
	{
		$categories .= "<a href='category.php?cid=".$nav_row['id']."'>" . $nav_row['name'] . "</a><br>";				// Process the main tree node
		array_push($exclude, $nav_row['id']);		// Add to the exclusion list
		if ( $nav_row['id'] < 6 )
		{ $top_level_on = $nav_row['id']; }
		
		$categories .= build_child($nav_row['id']);		// Start the recursive function of building the child tree
	}
}


function build_child($oldID)			// Recursive function to get all of the children...unlimited depth
{
	global $exclude, $depth, $mysql, $getcid;			// Refer to the global array defined at the top of this script
	$tempTree = '';	
	$child_query = $mysql->query("SELECT * FROM categories WHERE sub=" . $oldID);
	while ( $child = mysql_fetch_array($child_query))
	{
		if ( $child['id'] != $child['sub'] )
		{
			
			for ( $c=0;$c<$depth;$c++ )			// Indent over so that there is distinction between levels
			{ $tempTree .= "&nbsp;"; }
			$tempTree .= "- <a href='category.php?cid=".$child['id']."'>" . $child['name'] . "</a><br>";
			$depth++;		// Incriment depth b/c we're building this child's child tree  (complicated yet???)
			$tempTree .= build_child($child['id']);		// Add to the temporary local tree
			$depth--;		// Decrement depth b/c we're done building the child's child tree.
			array_push($exclude, $child['id']);			// Add the item to the exclusion list
		}
	}
	return $tempTree;		// Return the entire child tree
}

PHP:

so its showing perfectly categories & sub-cat or sub of sub-cat..

[COLOR="#0000CD"]TV[/COLOR]
-->LG
-->Samsung
-->Sony
[COLOR="#0000CD"]Computer[/COLOR]
-->Desktop
[COLOR="#B22222"]-->-->HP
-->-->DEELL[/COLOR]
-->Laptop
[COLOR="#B22222"]-->-->Apple
-->-->HP[/COLOR]
[COLOR="#0000CD"]Car[/COLOR]
-->Ford
-->Toyota

Code (markup):

its showing all together.
but i want it to show sub-cat only when its parent-cat is clicked (we may use if($_GET['cat_id'] == parentid) something like tht)
like if apple selected...it will only show

[COLOR="#0000CD"]TV[/COLOR]
[COLOR="#0000CD"]Computer[/COLOR]
-->Desktop
-->Laptop
[COLOR="#B22222"]-->-->Apple
-->-->HP[/COLOR]
[COLOR="#0000CD"]Car[/COLOR]

Code (markup):

plz help

 

add this line

if($_GET['cat_id']  == $nav_row['id']) </PHP] above

[PHP]
$categories .= build_child($nav_row['id']);

PHP:

BUt mind you this will show the deeper level categories ONLY if current category is the top level. i.e it wont show the 'Computer' if "apple' os choosen.

 

already tried that one. but in this case...when u click on the parent cat, it will show sub-cat (perfect till now)
but then when u click any sub-cat ...it doesnt show any sub-cat at all...just parent cat