mysql 添加行号

首先准备演示数

DROP TABLE IF EXISTS `computer_stu`;
CREATE TABLE `computer_stu` (
  `id` int(11) NOT NULL,
  `name` varchar(20) DEFAULT NULL,
  `score` float DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of computer_stu
-- ----------------------------
INSERT INTO `computer_stu` VALUES ('', 'Lily', '');
INSERT INTO `computer_stu` VALUES ('', 'Tom', '');
INSERT INTO `computer_stu` VALUES ('', 'Jim', '');
INSERT INTO `computer_stu` VALUES ('', 'Aric', '');
INSERT INTO `computer_stu` VALUES ('', 'Lucy', '');
INSERT INTO `computer_stu` VALUES ('', 'Andy', '');
INSERT INTO `computer_stu` VALUES ('', 'Ada', '');
INSERT INTO `computer_stu` VALUES ('', 'Jeck', '');

添加行号

SELECT
    (@rownumber :=@rownumber + 1) AS line,
    id,
    NAME,
    score
FROM
    (SELECT * FROM computer_stu) c,
    (SELECT @rownumber := 0) r;

结果如下

分组添加行号

SELECT
    @rownumber:=
    CASE
        WHEN @preScore = c.score THEN (@rownumber + 1)
        ELSE 1
    END  AS line,
    @preScore := c.score
    NAME,
    score
FROM
    (SELECT * FROM computer_stu ORDER BY computer_stu.score) c,
    (SELECT @rownumber := 0,@preScore:='') r;