WordPress代码 之 获取WordPress所有分类名字和ID

/**
 * 获取WordPress所有分类名字和ID
 * https://www.wpdaxue.com/show-wordpress-category.html
 */
function show_category(){
    global $wpdb;
    $request = "SELECT $wpdb->terms.term_id, name FROM $wpdb->terms ";
    $request .= " LEFT JOIN $wpdb->term_taxonomy ON $wpdb->term_taxonomy.term_id = $wpdb->terms.term_id ";
    $request .= " WHERE $wpdb->term_taxonomy.taxonomy = 'category' ";
    $request .= " ORDER BY term_id asc";
    $categorys = $wpdb->get_results($request);
    foreach ($categorys as $category) { //调用菜单
        $output = '<span>'.$category->name."(<em>".$category->term_id.'</em>)</span>';
        echo $output;
    }
}

<?php show_category(); ?>