工作中經常會用到這個場景，但是發現每次都會忘記要怎麼做，這裡特將oracle進行行轉列進行乙個歸納總結；
使用pivot進行動態行轉列
首先建立乙個測試表course：
create table ps_t_ly_test_course(
id number(11) primary key,
name varchar2(30),
tutor_id varchar2(11),
year number(4)
插入測試資料：
insert into ps_t_ly_test_course values (1,'語文課','10001',2018);
insert into ps_t_ly_test_course values (2,'數學課','10002',2018);
insert into ps_t_ly_test_course values (3,'化學課','10003',2018);
insert into ps_t_ly_test_course values (4,'物理課','10004',2018);
insert into ps_t_ly_test_course values (5,'生物課','10003',2018);
insert into ps_t_ly_test_course values (6,'體育課','10001',2018);
insert into ps_t_ly_test_course values (7,'歷史課','10001',2018);
insert into ps_t_ly_test_course values (8,'地理課','10002',2018);
insert into ps_t_ly_test_course values (9,'社會課','10004',2018);
insert into ps_t_ly_test_course values (10,'英語課','10003',2018);
insert into ps_t_ly_test_course values (11,'日語課','10003',2018);
insert into ps_t_ly_test_course values (12,'德語課','10003',2018);
insert into ps_t_ly_test_course values (13,'法語課','10003',2018);
insert into ps_t_ly_test_course values (14,'俄語課','10003',2018);
insert into ps_t_ly_test_course values (15,'科學課','10002',2018);
insert into ps_t_ly_test_course values (16,'哲學課','10002',2018);
insert into ps_t_ly_test_course values (17,'法學課','10002',2018);
insert into ps_t_ly_test_course values (18,'會計課','10001',2018);
insert into ps_t_ly_test_course values (19,'計算機課','10001',2018);
insert into ps_t_ly_test_course values (20,'人生課','10001',2018);
insert into ps_t_ly_test_course values (21,'語文課+','10001',2019);
insert into ps_t_ly_test_course values (22,'數學課+','10002',2019);
insert into ps_t_ly_test_course values (23,'化學課+','10003',2019);
insert into ps_t_ly_test_course values (24,'物理課+','10004',2019);
insert into ps_t_ly_test_course values (25,'生物課+','10003',2019);
insert into ps_t_ly_test_course values (26,'體育課+','10001',2019);
insert into ps_t_ly_test_course values (27,'歷史課+','10001',2019);
insert into ps_t_ly_test_course values (28,'地理課+','10002',2019);
insert into ps_t_ly_test_course values (29,'社會課+','10004',2019);
insert into ps_t_ly_test_course values (30,'英語課+','10003',2019);
insert into ps_t_ly_test_course values (31,'日語課+','10003',2019);
insert into ps_t_ly_test_course values (32,'德語課+','10003',2019);
insert into ps_t_ly_test_course values (33,'法語課+','10003',2019);
insert into ps_t_ly_test_course values (34,'俄語課+','10003',2019);
insert into ps_t_ly_test_course values (35,'科學課+','10002',2019);
insert into ps_t_ly_test_course values (36,'哲學課+','10002',2019);
insert into ps_t_ly_test_course values (37,'法學課+','10002',2019);
insert into ps_t_ly_test_course values (38,'會計課+','10001',2019);
insert into ps_t_ly_test_course values (39,'計算機課+','10001',2019);
insert into ps_t_ly_test_course values (40,'人生課+','10001',2019);
統計歷年各個導師教授的課程數
select *
from (select year, tutor_id from ps_t_ly_test_course) pivot(count(1) for tutor_id in('10001' as "導師1",
'10002' as "導師2",
'10003' as "導師3",
'10004' as "導師4"));
使用decode進行動態行轉列
select year,
count(decode(tutor_id, '10001', id, null)) 導師1,
count(decode(tutor_id, '10002', id, null)) 導師2,
count(decode(tutor_id, '10003', id, null)) 導師3,
count(decode(tutor_id, '10004', id, null)) 導師4
from ps_t_ly_test_course
group by year;
使用case when進行動態行轉列
select year,
count(case tutor_id when '10001' then id else null end) 導師1,
count(case tutor_id when '10002' then id else null end) 導師2,
count(case tutor_id when '10003' then id else null end) 導師3,
count(case tutor_id when '10004' then id else null end) 導師4
from ps_t_ly_test_course
group by year;
好了就介紹以上三種方法，寫的很簡陋，也沒有什麼說明，只為自己記錄使用；
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