Fetch a result object, if available, containing some rows of the nonblocking query
function mysql_async_query_result( resource $link_identifier = NULL, ): ?resource;
resource $link_identifier = NULL- The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If no connection is found or established, an E_WARNING level error is generated.
resource- - A mysql result object, or null if one isn't ready yet.