Mysql 行转列

1. 创建表:

create table tb(
ID int,
username varchar(20),
CN_SCORE float,
MATH_SCORE float,
EN_SCORE float
);

2. 插入数据:

INSERT INTO tb values(1,'lisi',87,65,75);
INSERT INTO tb values(2,'michale',78,95,81);
INSERT INTO tb values(3,'xiaocxiao',97,78,91);
INSERT INTO tb values(4,'zhangsan',80,55,75));

3. 补数据,添加个total:

 alter table tb add column total float after username;

update tb set total=(CN_SCORE+MATH_SCORE+EN_SCORE) WHERE ID IN(1,2,3,4);

或下面的形式:

UPDATE test
　　SET name = CASE id
　　　　WHEN 1 THEN 3
　　　　WHEN 2 THEN 4
　　　　WHEN 3 THEN 5
　　END
WHERE id IN (1,2,3)

4. 开始列转行:

select username, total, '语文' COURSE, CN_SCORE as SCORE from tb
union
select username, total,'数学' COURSE, MATH_SCORE as SCORE from tb
union
select username,total, '英语' COURSE, EN_SCORE as SCORE from tb
order by username,COURSE;

ID	username	total	CN_SCORE	MATH_SCORE	EN_SCORE
1	lisi	227	87	65	75
2	michale	254	78	95	81
3	xiaoxiao	266	97	78	91
4	zhangsan	210	80	55	75

转换后:

username	total	COURSE	SCORE
lisi	227	语文	87
lisi	227	英语	75
lisi	227	数学	65
michale	254	数学	95
michale	254	英语	81
michale	254	语文	78
xiaoxiao	266	语文	97
xiaoxiao	266	英语	91
xiaoxiao	266	数学	78
zhangsan	210	语文	80
zhangsan	210	英语	75
zhangsan	210	数学	55