MYSQL auto_increment_increment

Question

我想在一个mysql数据库中auto_increment两个不同的表,第一个是1的倍数,另一个是5,这可能是使用auto_increment功能,因为我似乎只能全局设置auto_increment_increment.

如果auto_increment_increment不是一个选项,那么复制它的最佳方法是什么

Answer 1

更新版本:仅使用单个id字段.这很可能不是原子的,所以如果需要并发,请在事务中使用:

http://sqlfiddle.com/#!2/a4ed8/1

CREATE TABLE IF NOT EXISTS person (
   id  INT NOT NULL AUTO_INCREMENT,
   PRIMARY KEY ( id )
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;

CREATE TRIGGER insert_kangaroo_id BEFORE INSERT ON person FOR EACH ROW BEGIN
  DECLARE newid INT;

  SET newid = (SELECT AUTO_INCREMENT
               FROM information_schema.TABLES
               WHERE TABLE_SCHEMA = DATABASE()
               AND TABLE_NAME = 'person'
              );

  IF NEW.id AND NEW.id >= newid THEN
    SET newid = NEW.id;
  END IF;

  SET NEW.id = 5 * CEILING( newid / 5 );
END;

旧的,不工作的"解决方案"(之前的插入触发器无法看到当前的自动增量值):

http://sqlfiddle.com/#!2/f4f9a/1

CREATE TABLE IF NOT EXISTS person (
   secretid  INT NOT NULL AUTO_INCREMENT,
   id        INT NOT NULL,
   PRIMARY KEY ( secretid )
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;

CREATE TRIGGER update_kangaroo_id BEFORE UPDATE ON person FOR EACH ROW BEGIN
  SET NEW.id = NEW.secretid * 5;
END;

CREATE TRIGGER insert_kangaroo_id BEFORE INSERT ON person FOR EACH ROW BEGIN
  SET NEW.id = NEW.secretid * 5; -- NEW.secretid is empty = unusuable!
END;