`name` varchar(32) CHARACTER SET utf8 NOT NULL,
`name_short` varchar(8) CHARACTER SET utf8 NOT NULL,
`unit_group` int(11) NOT NULL,
+ `prec` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `fk_units_group_idx` (`unit_group`),
CONSTRAINT `fk_units_group` FOREIGN KEY (`unit_group`) REFERENCES `unit_groups` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION