CREATE TABLE `t_test_type` (
	`f_num` INT(11) NULL DEFAULT NULL,
	`f_str` CHAR(50) NULL DEFAULT NULL
)
ENGINE=MyISAM
;

select * from t_test_type;
1;1
2;2
3;3

select * from t_test_type where f_str < "2.0";
1;1
2;2


select * from t_test_type where f_str < 2.0;
1;1