Max of sum query

Question

I\'m trying to write a query that will list student(s) enrolled with the maximum total credit points.

Here is my query:

    SELECT s.S_ID,
       s.S_LAS         


        

Answer 1

If you build your query one join at a time, you will notice, first, that you don't need any of those inline views. You can do it very simply with one CTE definition and a subquery.

WITH
student AS
( SELECT  1 s_id, 'Jones' s_last, 'Sally' s_first FROM dual UNION ALL
  SELECT  2, 'Smith', 'Pete' FROM dual UNION ALL
  SELECT  3, 'DeThroned', 'Kate' FROM dual
),
enrollment AS
( SELECT  1 s_id, 10 c_sec_id FROM dual UNION ALL
  select  1, 11 FROM dual UNION ALL
  select  2, 11 FROM dual UNION ALL
  SELECT  3, 12 FROM dual
),
course_section AS
( SELECT  10 c_sec_id, 101 course_no FROM dual UNION ALL
  SELECT  11, 102 FROM dual UNION ALL
  SELECT  12, 103 FROM dual
),
course AS
( SELECT  101 course_id, 1 credits FROM dual UNION ALL
  SELECT  102, 2 FROM dual UNION ALL
  SELECT  103, 3 FROM dual
),
StudentCredit AS
( SELECT  s.s_id, s_last, s_first, sum( c.credits ) AS TotalCredits
  FROM    student s
  JOIN    enrollment e
    ON    e.s_id = s.s_id
  JOIN    course_section cs
    ON    cs.c_sec_id = e.c_sec_id
  JOIN    course c
    ON    c.course_id = cs.course_no
  GROUP BY s.s_id, s_last, s_first
)
SELECT  *
FROM    StudentCredit
WHERE   TotalCredits = (
          SELECT  MAX( TotalCredits )
          FROM    StudentCredit
        );