Get stuff by name (WordPress)

get_by_name.php

<?php
/**
 * Get stuff ID by nicename
 * @param $nicename string The nicename (i.e: post-slug) to get the ID for
 * @param $type string The table that will be queried: posts (default), term, users
 * @return integer The ID for the requested object, false if nothing found
 */
function get_by_name($nicename, $type="posts"){
    global $wpdb;
    if ( empty($type) OR $type === 'post'){
        $query = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE post_name = $nicename");
    } elseif ( $type === 'term' ) {
        $query = $wpdb->get_var("SELECT term_id FROM $wpdb->terms WHERE slug = $nicename");
    } elseif ( $type === 'user' ) {
        $query = $wpdb->get_var("SELECT ID FROM $wpdb->users WHERE user_login = $nicename");
    }
    if ( $query ) return $query;
    else return false;
}
?>