Oracle列與行轉換交叉表

1.行轉列 利用decode 函數

create table course(
       id number primary key,
       name nvarchar2(200),
       comments nvarchar2(200)
)

truncate table course;
insert into course values(1, 'Chinese', '87');
insert into course values(2, 'Mathematic', '90');
insert into course values(3, 'Chinese', '34');
insert into course values(4, 'English', '98');
insert into course values(5, 'Janpanese', '22');
insert into course values(6, 'English', '189');
insert into course values(7, 'Mathematic', '34');

commit;

select sum(decode(name, 'Chinese', comments, null)) Chinese, 
       sum(decode(name, 'Mathematic', comments, null)) Mathematic,
       sum(decode(name, 'English', comments, null)) English,
       sum(decode(name, 'Janpanese', comments, null)) Janpanese
from course;

2. 列轉行 

with b as
(
  select sum(decode(name, 'Chinese', comments, null)) Chinese, 
         sum(decode(name, 'Mathematic', comments, null)) Mathematic,
         sum(decode(name, 'English', comments, null)) English,
         sum(decode(name, 'Janpanese', comments, null)) Janpanese
  from course
)
select 'Mathematic' course,
decode(1, 1, Mathematic, Mathematic) Mathematic
from b
union all
select 'Chinese' course, 
decode(1, 1, Chinese, Chinese) name
from b
union all
select 'English' course,
decode(1, 1, English, English) name
from b
union all
select 'Janpanese' course,
decode(1, 1, Janpanese, Janpanese) name
from b