To get the URL Alias of a node

To get the URL Alias of a node:

$system_path = 'node/'.arg(1);

$current_path = drupal_get_path_alias($system_path);

Using a Normal DB query, to get the node id form the node tabel like this,

$nid = db_result(db_query("SELECT nid FROM {term_node} 

WHERE tid = %d", $tid)); 

$system_path = 'node/'.$nid; 
$current_path = drupal_get_path_alias($system_path);

One more important information,if you opening a popup window,you are in 

need to get the base url of the page that you opens the pop up.Then you 

need to use this,

$basename = $_SERVER['HTTP_REFERER']; 

It will refer the base path of the page that you have opens the pop up..