Mysql 本身不提供序列机制，但是可以通过函数来模拟实现序列
CREATE TABLE IF NOT EXISTS `sequence` (
`id` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
`current_value` int(11) NULL DEFAULT NULL,
`increment` int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci;
INSERT INTO `sequence` (`id`, `current_value`, `increment`) VALUES ('demo', 0, 1);
DROP FUNCTION IF EXISTS `current_sequence`;
DELIMITER //
CREATE FUNCTION `current_sequence`(seq_id VARCHAR(255)) RETURNS int(11)
READS SQL DATA
DETERMINISTIC
BEGIN
DECLARE VALUE INTEGER;
SET VALUE = 0;
SELECT current_value INTO VALUE FROM sequence WHERE id = seq_id;
RETURN VALUE;
END//
DELIMITER ;
DROP FUNCTION IF EXISTS `next_sequence`;
DELIMITER //
CREATE FUNCTION `next_sequence`(seq_id VARCHAR(255)) RETURNS int(11)
DETERMINISTIC
BEGIN
UPDATE sequence SET current_value = current_value + increment WHERE id = seq_id;
RETURN current_sequence(seq_id);
END//
DELIMITER ;
