行列转置（Oracle）

一、Oracle行列转置

1、行转列

（1）创建表格、插入测试数据

create table student(
id number,
name varchar2(20),
course varchar2(20),
score number
)

（2）方法一：使用wm_concat()函数

select id, name, wm_concat(score) scores from student group by id, name;

（3）方法二：使用decode()函数

select id,name,sum(decode(course,'Chinese',score,null)) "Chinese",
sum(decode(course,'Math',score,null)) "Math",
sum(decode(course,'English',score,null)) "English"
from student
group by id,name

（4）方法三：使用case表达式

select id,name,sum(case when course='Chinese' then score end) "Chinese",
sum(case when course='Math' then score end) "Math",
sum(case when course='English' then score end) "English"
from student
group by id,name

2、列转行

（1）建表

create table scores as
select id,name,sum(case when course='Chinese' then score end) "Chinese",
sum(case when course='Math' then score end) "Math",
sum(case when course='English' then score end) "English"
from student
group by id,name
order by i

（2）方法一：合并查询union

select id,name,'Chinese' as course from scores
union
select id,name,'Math' as course from scores
union
select id,name,'English' as course from scores