MySQL模拟Oracle序列sequence

DROP TABLE IF EXISTS sys_sequence ;

CREATE TABLE sys_sequence (

  seq_name VARCHAR (50) NOT NULL,

  curr_value BIGINT NOT NULL DEFAULT 0,

  increment_by INT NOT NULL DEFAULT 1,

  PRIMARY KEY (seq_name)

) ENGINE = INNODB ;

INSERT INTO sys_sequence VALUES ('SEQ_TEST_NO',10000,1);

DELIMITER $$

DROP FUNCTION IF EXISTS currval $$

CREATE

    /*[DEFINER = { user | CURRENT_USER }]*/

    FUNCTION currval(v_seq_name VARCHAR (50))

    RETURNS BIGINT

    /*LANGUAGE SQL

    | [NOT] DETERMINISTIC

    | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }

    | SQL SECURITY { DEFINER | INVOKER }

    | COMMENT 'string'*/

    BEGIN

    DECLARE v_currval BIGINT;

      SET v_currval = 1 ;

      SELECT

        curr_value INTO v_currval

      FROM

        sys_sequence

      WHERE seq_name = v_seq_name ;

      RETURN v_currval ;

    END$$

DELIMITER ;

-- SELECT `currval`('SEQ_TEST_NO');

DELIMITER $$

DROP FUNCTION IF EXISTS `nextval` $$

CREATE FUNCTION `nextval` (`v_seq_name` VARCHAR (50)) RETURNS BIGINT (20) CONTAINS SQL

BEGIN

  UPDATE

    sys_sequence

  SET

    `curr_value` = last_insert_id(`curr_value` + `increment_by`)

  WHERE `seq_name` = v_seq_name ;

  RETURN last_insert_id();

END $$

DELIMITER ;