oracle sql 在同一查询中过滤

Question

I have a join_table as follows for a single person with id = 123.

join_time

id  subject join_date
123 MATH    03-MAY-19
123 MATH    12-MAR-15
123 CS      05-JUN-12
123 CS      24-JUL-12
123 CS      27-JUN-14
123 HIST    18-AUG-14
123 HIST    19-DEC-12
123 SCI     20-MAY-02
123 SCI     26-JUL-93

My oracle sql output should be 1 per subject with the latest joining date and also the subject should be formatted as below:

id  subject                 join_date
123 Maths                   03-MAY-19
123 Computer Science        27-JUN-14
123 History                 18-AUG-14
123 Science                 20-MAY-02

suggestions pls?

Answer 1

Seems you need aggregation function and group by

    select id, subject, max(join_date)
    from my_table 
    group by id, subject