MySQL自动为查询数据结果加序号

DROP TABLE IF EXISTS tb_score;
CREATE TABLE tb_score(
    id INT(11) NOT NULL auto_increment,
    userid VARCHAR(20) NOT NULL COMMENT '用户id',
    subject VARCHAR(20) COMMENT '科目',
    score DOUBLE COMMENT '成绩',
    PRIMARY KEY(id)
)ENGINE = INNODB DEFAULT CHARSET = utf8;
INSERT INTO tb_score(userid,subject,score) VALUES ('001','语文',90);
INSERT INTO tb_score(userid,subject,score) VALUES ('001','数学',92);
INSERT INTO tb_score(userid,subject,score) VALUES ('001','英语',80);
INSERT INTO tb_score(userid,subject,score) VALUES ('002','语文',88);
INSERT INTO tb_score(userid,subject,score) VALUES ('002','数学',90);
INSERT INTO tb_score(userid,subject,score) VALUES ('002','英语',75.5);
INSERT INTO tb_score(userid,subject,score) VALUES ('003','语文',70);
INSERT INTO tb_score(userid,subject,score) VALUES ('003','数学',85);
INSERT INTO tb_score(userid,subject,score) VALUES ('003','英语',90);
INSERT INTO tb_score(userid,subject,score) VALUES ('003','政治',82);

SELECT
	id,userid,subject,score, (@i :=@i + 1) AS '序号'
FROM
	tb_score,
	(SELECT @i := 0) AS itable;

+----+--------+---------+-------+--------+
| id | userid | subject | score | 序号   |
+----+--------+---------+-------+--------+
|  1 | 001    | 语文    |    90 |      1 |
|  2 | 001    | 数学    |    92 |      2 |
|  3 | 001    | 英语    |    80 |      3 |
|  4 | 002    | 语文    |    88 |      4 |
|  5 | 002    | 数学    |    90 |      5 |
|  6 | 002    | 英语    |  75.5 |      6 |
|  7 | 003    | 语文    |    70 |      7 |
|  8 | 003    | 数学    |    85 |      8 |
|  9 | 003    | 英语    |    90 |      9 |
| 10 | 003    | 政治    |    82 |     10 |
+----+--------+---------+-------+--------+
10 rows in set (0.00 sec)

SELECT
	*, (@i :=@i + 1) AS '序号'
FROM
	tb_score;

+----+--------+---------+-------+--------+
| id | userid | subject | score | 序号   |
+----+--------+---------+-------+--------+
|  1 | 001    | 语文    |    90 |     11 |
|  2 | 001    | 数学    |    92 |     12 |
|  3 | 001    | 英语    |    80 |     13 |
|  4 | 002    | 语文    |    88 |     14 |
|  5 | 002    | 数学    |    90 |     15 |
|  6 | 002    | 英语    |  75.5 |     16 |
|  7 | 003    | 语文    |    70 |     17 |
|  8 | 003    | 数学    |    85 |     18 |
|  9 | 003    | 英语    |    90 |     19 |
| 10 | 003    | 政治    |    82 |     20 |
+----+--------+---------+-------+--------+
10 rows in set (0.00 sec)

SET @i=0;
SELECT id,userid,subject,score,@i:=@i+1 AS '序号' 
FROM tb_score;

+----+--------+---------+-------+--------+
| id | userid | subject | score | 序号   |
+----+--------+---------+-------+--------+
|  1 | 001    | 语文    |    90 |      1 |
|  2 | 001    | 数学    |    92 |      2 |
|  3 | 001    | 英语    |    80 |      3 |
|  4 | 002    | 语文    |    88 |      4 |
|  5 | 002    | 数学    |    90 |      5 |
|  6 | 002    | 英语    |  75.5 |      6 |
|  7 | 003    | 语文    |    70 |      7 |
|  8 | 003    | 数学    |    85 |      8 |
|  9 | 003    | 英语    |    90 |      9 |
| 10 | 003    | 政治    |    82 |     10 |
+----+--------+---------+-------+--------+
10 rows in set (0.00 sec)