Det här borde få dig igång -
CREATE TABLE users
(user_id varchar2(9), user_name varchar2(11))
;
INSERT ALL
INTO users (user_id, user_name)
VALUES ('1', 'user_1')
INTO users (user_id, user_name)
VALUES ('2', 'user_2')
INTO users (user_id, user_name)
VALUES ('3', 'user_3')
INTO users (user_id, user_name)
VALUES ('4', 'user_4')
SELECT * FROM dual
;
CREATE TABLE exam
(exam_id varchar2(9), exam_name varchar2(11))
;
INSERT ALL
INTO exam (exam_id, exam_name)
VALUES ('1', 'exam_1')
INTO exam (exam_id, exam_name)
VALUES ('2', 'exam_2')
INTO exam (exam_id, exam_name)
VALUES ('3', 'exam_3')
SELECT * FROM dual
;
CREATE TABLE exam_user
(exam_id varchar2(9), user_id varchar2(9), exam_date varchar2(11))
;
INSERT ALL
INTO exam_user (exam_id, user_id, exam_date)
VALUES ('1', '1', '2017')
INTO exam_user (exam_id, user_id, exam_date)
VALUES ('1', '2', '2018')
INTO exam_user (exam_id, user_id, exam_date)
VALUES ('1', '3', '2017')
INTO exam_user (exam_id, user_id, exam_date)
VALUES ('2', '3', '2018')
SELECT * FROM dual
;
Fråga -
SELECT * FROM (
SELECT U.USER_ID, U.USER_NAME, E.EXAM_NAME,EU.EXAM_DATE
FROM USERS U, EXAM E, EXAM_USER EU
WHERE U.USER_ID = EU.USER_ID(+)
AND E.EXAM_ID(+) = EU.EXAM_ID
ORDER BY U.USER_ID
)
PIVOT (MAX(EXAM_DATE) FOR EXAM_NAME IN ('exam_1' as exam_1, 'exam_2' as exam_2,'exam_3' as exam_3))
order by 1
;
Utdata -
USER_ID USER_NAME EXAM_1 EXAM_2 EXAM_3
1 user_1 2017 (null) (null)
2 user_2 2018 (null) (null)
3 user_3 2017 2018 (null)
4 user_4 (null) (null) (null)