When I execute the statement below:

SELECT concat(case ip_protocol when 6 then 'TCP' when 17 then 'UDP' else 'OTHER' end, ', PORT ', repeat(' ', 5 - length(if(port is NULL, 0, port))), if(port is NULL, 0, port)) as protocol, concat(case ip_protocol when 6 then 'TCP' when 17 then 'UDP' else 'OTHER' end, if(port is NULL, 0, port)) as id, sum(byte_subtotal) as total FROM usage_sum_minute WHERE from_unixtime(time_min * 60) between '2008-02-03 14:00:00' and '2008-03-05 13:59:00' GROUP BY protocol ORDER BY total DESC LIMIT 0, 20

DB schema:
CREATE TABLE `ascot`.`usage_sum_minute` (
  `id` int(11) NOT NULL auto_increment,
  `igateway_id` smallint(5) NOT NULL,
  `time_min` int(11) NOT NULL,
  `user_name` varchar(255) default NULL,
  `mac_local` varchar(80) NOT NULL,
  `ip_local` bigint(20) NOT NULL,
  `ip_remote` bigint(20) NOT NULL,
  `ip_protocol` smallint(5) NOT NULL,
  `port` smallint(6) default NULL,
  `domain_name` char(80) default NULL,
  `url` varchar(1024) default NULL,
  `byte_subtotal` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `id` (`id`),
  KEY `index_igateway` (`igateway_id`),
  KEY `index_protocol` (`ip_protocol`),
  KEY `index_minute` (`time_min`),
  KEY `index_user` (`user_name`),
  KEY `index_port` (`port`),
  KEY `index_ip` (`ip_remote`)
) ENGINE=InnoDB AUTO_INCREMENT=505699 DEFAULT CHARSET=latin1

It give an exception "No Dialect mapping for JDBC type: -4"