Question from the Drupal 7 test

$query = db_select('node', 'n')
->fields('n', array('nid', 'title'))
->condition('created', REQUEST_TIME - 3600)
->execute();

$query = "SELECT nid, title FROM {node} WHERE created > REQUEST_TIME - 3600";

$query = db_select("SELECT nid, title FROM {node} WHERE created > REQUEST_TIME - 3600");

$query = db_query("SELECT nid, title FROM {node} WHERE created > :created", array(
':created' => REQUEST_TIME - 3600,
));

$query = db_select("SELECT nid, title FROM {node} WHERE created > :created", array(
':created' => REQUEST_TIME - 3600,
));

$query = db_query("SELECT nid, title FROM {node} WHERE created > REQUEST_TIME - 3600");