mysql通过表和function模拟oracle的sequence

CREATE TABLE `sequence` (
`seq_name` varchar(45) NOT NULL COMMENT 'sequence名',
`seq_value` bigint(20) NOT NULL COMMENT 'sequence值',
`increment` int(3) NOT NULL DEFAULT '1' COMMENT '步进',
PRIMARY KEY (`seq_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;

INSERT INTO `sequence` VALUES ('SEQ_CERT', '26', '1');

delimiter //

CREATE FUNCTION nextValue (s varchar(50)) RETURNS int(10)

BEGIN
DECLARE r integer;
set r = 0;
update sequence set seq_value = seq_value + increment where seq_name = s;
select seq_value into r from sequence where seq_name = s;
return r;
END

//
delimiter ;

select nextValue('SEQ_CERT');