mysql模仿oracle序列

DROP TABLE IF EXISTS sequence;

CREATE TABLE sequence (
idval  INT UNSIGNED AUTO_INCREMENT,
PRIMARY KEY (idval)
) ENGINE=InnoDB;

DROP FUNCTION IF EXISTS nextval;
DELIMITER $
CREATE FUNCTION nextval ()
RETURNS INTEGER
CONTAINS SQL
BEGIN
declare id long;
insert into sequence () values();
select last_insert_id() into id;
return id;
END$
DELIMITER ;

mysql> SELECT nextval();
+-----------+
| nextval() |
+-----------+
|        89 |
+-----------+