-- Sequence 管理表 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;  -- 取当前值的函数 DROP FUNCTION IF EXISTS currval; DELIMITER $ CREATE FUNCTION currval (seq_name VARCHAR(50))    RETURNS INTEGER     LANGUAGE SQL    DETERMINISTIC   CONTAINS SQL    SQL SECURITY DEFINER    COMMENT '' BEGIN  DECLARE value INTEGER;  SET value = 0;     SELECT current_value INTO value         FROM sequence       WHERE name = seq_name;     RETURN value; END $ DELIMITER ;  -- 取下一个值的函数 DROP FUNCTION IF EXISTS nextval; DELIMITER $ CREATE FUNCTION nextval (seq_name VARCHAR(50))    RETURNS INTEGER     LANGUAGE SQL    DETERMINISTIC   CONTAINS SQL    SQL SECURITY DEFINER    COMMENT '' BEGIN  UPDATE sequence         SET current_value = current_value + increment         WHERE name = seq_name;     RETURN currval(seq_name); END $ DELIMITER ;  -- 更新当前值的函数 DROP FUNCTION IF EXISTS setval; DELIMITER $ CREATE FUNCTION setval (seq_name VARCHAR(50), value INTEGER)   RETURNS INTEGER     LANGUAGE SQL    DETERMINISTIC   CONTAINS SQL    SQL SECURITY DEFINER    COMMENT '' BEGIN  UPDATE sequence         SET current_value = value      WHERE name = seq_name;     RETURN currval(seq_name); END $ DELIMITER ;  /* -- 测试 INSERT INTO sequence VALUES ('TestSeq', 0, 1); SELECT SETVAL('TestSeq', 10); SELECT CURRVAL('TestSeq'); SELECT NEXTVAL('TestSeq'); */