MySQL recursive tree search

Question

I have a database with a tree of names that can go down a total of 9 levels deep and I need to be able to search down a signal branch of the tree from any point on the branc

Answer 1

Have you thought about using a recursive loop? i use a loop for a cms i built on top of codeigniter that allows me to start anywhere in the site tree and will then subsequently filter trhough all the children> grand children > great grand children etc. Plus it keeps the sql down to short rapid queries opposed to lots of complicated joins. It may need some modifying in your case but i think it could work.

/**
 * build_site_tree
 *
 * @return void
 * @author Mike Waites
**/
public function build_site_tree($parent_id)
{
    return $this->find_children($parent_id);
}

/** end build_site_tree **/

// -----------------------------------------------------------------------

/**
 * find_children
 * Recursive loop to find parent=>child relationships
 *
 * @return array $children
 * @author Mike Waites
**/
public function find_children($parent_id)
{
    $this->benchmark->mark('find_children_start');

    if(!class_exists('Account_model'))
            $this->load->model('Account_model');

    $children = $this->Account_model->get_children($parent_id);

    /** Recursively Loop over the results to build the site tree **/
    foreach($children as $key => $child)
    {
        $childs = $this->find_children($child['id']);

        if (count($childs) > 0)
                $children[$key]['children'] = $childs;
    }

    return $children;

    $this->benchmark->mark('find_children_end');
}

/** end find_children **/

As you can see this is a pretty simplfied version and bear in mind this has been built into codeigniter so you will need to modyfy it to suite but basically we have a loop that calls itself adding to an array each time as it goes. This will allow you to get the whole tree, or even start from a point in the tree as long as you have the parent_id avaialble first!

Hope this helps