<?xml version="1.0" encoding="ISO-8859-1"?>
<slide>
	<title>Path Strings</title>

	<example><![CDATA[Id | ParentId | PathString  | Name         | Depth
---+----------+-------------+--------------+------
87 |        2 | /87/        | Countries    |  2
88 |       87 | /87/88/     | Belgium      |  3
89 |       87 | /87/89/     | Netherlands  |  3
91 |       89 | /87/89/91/  | Business     |  4
92 |       89 | /87/89/92/  | Economy      |  4 
90 |       87 | /87/90/     | Germany      |  3]]></example>
<break/>
	<blurb>Adding a node:</blurb>
<break/>
	<example><![CDATA[function add_node( parent, name )
{
	$parent_info =
		SELECT *
		FROM tree
		WHERE Id = $parent;
	
	INSERT INTO tree(Id, Name) VALUES( NULL, $name );
	
	$last_id = LAST INSERT ID;
	UPDATE tree
		SET
			ParentId = $parent,
			PathString = $parent_info['PathString'] . $last_id . "/",
			Depth = $parent['Depth'] + 1
		WHERE Id = $last_id
}]]></example>
</slide>
  
