Get total (parrent & child) comment

functions.php

<?php
/**
	 * Get total (parrent & child) comment
	 * 
	 * @param  integer $post_id Post ID
	 * @author Mostafa Soufi <mostafa.soufi@hotmail.com>
	 */
	public function get_total_count( $post_id ) {

		global $wpdb, $table_prefix;

		$result = $wpdb->get_row( $wpdb->prepare("SELECT count(*) AS parrent_count, comment_ID AS last_parrent, ( SELECT COUNT(*) FROM ".$table_prefix."comments WHERE comment_parent = last_parrent AND comment_approved = '1' ) AS childs FROM ".$table_prefix."comments WHERE comment_post_ID = '%s' AND comment_approved = '1'", $post_id) );

		if( $result ) {
			return strval( $result->parrent_count + $result->childs );
		}

	}