Creating a "guide bar" like this, above a web page by php+mysql?

Question

I want to create a "guide bar" (I don't know its right name). I've got a table called cat that has the following data:

catid        catname         parentid
1            news            null
2            sport           1
3            health          1
4            tennis          2
5            football        2
6            soccer          5

My page receives: $catid=6, and I want to create:

news>sport>football>soccer

Answer 1

First get your data from database and build an array

$q = mysql_query("SELECT catid, catname, parentid FROM cat");
$pages = array();
while($r = mysql_fetch_assoc($q)) {
    $pages[$r['catid']] = array('catname' => $r['catname'], 'parentid' => $r['parentid']);
}

Use a recursive function to build the breadcrumbs:

function build_breadcrumbs($pages, $catid) {
    if(is_null($catid) || empty($catid)) return;
    return build_breadcrumbs($pages, $pages[$catid]['parentid']).$pages[$catid]['catname'].' > ';
}

The function returns the parent's breadcrumbs + the current breadcrumb. Use the function like this:

$catid = 6;
$breadcrumbs = trim(build_breadcrumbs($pages, $catid), ' >');
echo $breadcrumbs;

Or, if you like arrays more, you can create a function like this:

function build_breadcrumbs($pages, $catid) {
    if(is_null($catid) || empty($catid)) return array();
    return array_merge(build_breadcrumbs($pages, $pages[$catid]['parent']), array($pages[$catid]['name']));
}

and use it with implode:

$catid = 6;
$breadcrumbs = implode(' > ', build_breadcrumbs($pages, $catid));
echo $breadcrumbs;

That gives you the option to define the separator outside the function. Hope that helps.