Drupal 6 migration example

import.php

<?php  
function import_nodes() {  
  db_query('DELETE FROM {node} WHERE `nid` > 1');
  db_query('ALTER TABLE {node} AUTO_INCREMENT = 2');
  db_query('DELETE FROM {node_revision} WHERE `nid` > 1');
  db_query('ALTER TABLE {node_revision} AUTO_INCREMENT = 2');
  db_query('DELETE FROM {field_revision_body} WHERE `entity_id` > 1');
  db_query('DELETE FROM {field_data_body} WHERE `entity_id` > 1');
  db_query('DELETE FROM {node_comment_statistics} WHERE `nid` > 1');
  db_query('TRUNCATE TABLE {url_alias}');

  db_set_active('drupal6');
  $result = db_query('SELECT n.`nid`, n.`title`, n.`created`, u.`dst` as alias, n.`type`,
  (SELECT `body` FROM {node_revisions} WHERE `nid` = n.`nid` ORDER BY `vid` DESC LIMIT 1) as body,
  (SELECT IF(`format`=3, "php_code", "full_html") FROM {node_revisions} WHERE `nid` = n.`nid` ORDER BY `vid` DESC LIMIT 1) as format
  FROM {node} n 
  LEFT JOIN {url_alias} u ON u.`src` = CONCAT("node/", n.`nid`)
  WHERE n.`type` = "page"')->fetchAll();
  db_set_active(); 
  foreach($result as $key => $node) {
    $n = new stdClass();
    $n->title = $node->title;
    $n->type = $node->type;
    $n->language = 'und';
    $n->created = $node->created;
    $n->body[$n->language][0]['value'] = $node->body;
    $n->body[$n->language][0]['format'] = $node->format;
    $n->path = array('alias' => $node->alias);
    node_save($n);
    unset($n);
  }
  return 'Import Complete';
}

 if (isset($_GET['go'])) echo import_nodes();
 else echo '<a href="?go">Import Nodes</a>';
?>