MySQL序列解决方案

-- 定义序列表
DROP TABLE IF EXISTS sequence;
CREATE TABLE sequence (
 name VARCHAR(50) NOT NULL,
 current_value INT NOT NULL,
 increment INT NOT NULL DEFAULT 1,
 PRIMARY KEY (name)
) ENGINE=InnoDB;
 
-- 获取当前序列号
DROP FUNCTION IF EXISTS currval;
DELIMITER $
CREATE FUNCTION currval (seq_name VARCHAR(50))
RETURNS INTEGER
CONTAINS SQL
BEGIN
 DECLARE value INTEGER;
 SET value = 0;
 SELECT current_value INTO value
 FROM sequence
 WHERE name = seq_name;
 RETURN value;
END$
DELIMITER ;
 
-- 获取下一个序列号
DROP FUNCTION IF EXISTS nextval;
DELIMITER $
CREATE FUNCTION nextval (seq_name VARCHAR(50))
RETURNS INTEGER
CONTAINS SQL
BEGIN
 UPDATE sequence SET current_value = current_value + increment
 WHERE name = seq_name;
 RETURN currval(seq_name);
END$
DELIMITER ;
 
-- 重设序列号
DROP FUNCTION IF EXISTS setval;
DELIMITER $
CREATE FUNCTION setval (seq_name VARCHAR(50), value INTEGER)
RETURNS INTEGER
CONTAINS SQL
BEGIN
 UPDATE sequence SET current_value = value
 WHERE name = seq_name;
 RETURN currval(seq_name);
 END$
DELIMITER ;
 
-- 初始化数据
INSERT INTO sequence VALUES ('SAMPLE', 1, 1);
 
-- 测试
SELECT currval('SAMPLE');
SELECT nextval('SAMPLE');
SELECT nextval('SAMPLE');
SELECT setval('SAMPLE',150);
SELECT currval('SAMPLE');
SELECT nextval('SAMPLE');
SELECT nextval('SAMPLE');