from_unixtime((datetime DIV 86400)*86400)

set @timemin=UNIX_TIMESTAMP('2013-09-25 00:00:00')-1;
set @timemax=UNIX_TIMESTAMP('2013-09-25 23:59:59');
SELECT t0.value , from_unixtime((t0.date_time div 86400)* 86400), from_unixtime(t0.date_time)
FROM tbl_tag_data_hour t0
WHERE t0.id_tag_data_Kip=95[SRC XML]

set @timemin=UNIX_TIMESTAMP('2013-09-25 00:00:00')-1;
set @timemax=UNIX_TIMESTAMP('2013-09-25 23:59:59');
SELECT t0.value , from_unixtime((t0.date_time div 86400)* 86400), from_unixtime(t0.date_time)
FROM tbl_tag_data_hour t0
WHERE t0.id_tag_data_Kip=95
AND t0.date_time>@timemin  AND t0.date_time< @timemax order by t0.id desc ;

CREATE TABLE `tbl_tag_data_hour` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`id_tag_data_Kip` INT(11) NOT NULL,
	`value` FLOAT NOT NULL,
	`date_time` INT(11) NOT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=45009
AVG_ROW_LENGTH=43;