Working with nested loops in pl/sql but not displaying the proper output - database

Question

SET SERVEROUTPUT ON SIZE 4000;
DECLARE
call_id COURSE.CALL_ID%type;
sec_num COURSE_SECTION.SEC_NUM%type;
fname STUDENT.S_FIRST%TYPE ;
lname STUDENT.S_LAST%TYPE;
CURSOR c_info is
SELECT CALL_ID , SEC_NUM
FROM COURSE_SECTION ,COURSE,TERM
WHERE COURSE_SECTION.COURSE_ID = COURSE.COURSE_ID
AND TERM.TERM_ID = COURSE_SECTION.TERM_ID
AND TERM.TERM_DESC = 'Summer 2007' ;
CURSOR S_NAME IS
SELECT DISTINCT S_FIRST, S_LAST
FROM STUDENT,COURSE_SECTION,TERM,ENROLLMENT
WHERE TERM.TERM_ID = COURSE_SECTION.TERM_ID
AND COURSE_SECTION.C_SEC_ID = ENROLLMENT.C_SEC_ID
AND COURSE_SECTION.TERM_ID=TERM.TERM_ID
AND ENROLLMENT.S_ID = STUDENT.S_ID
AND TERM.TERM_DESC LIKE 'Summer 2007';
BEGIN
OPEN c_info;
LOOP
FETCH c_info INTO call_id , sec_num ;
EXIT WHEN c_info%notfound;
DBMS_OUTPUT.PUT_LINE('==================================');
DBMS_OUTPUT.PUT_LINE(call_id || ' ' || 'Sec. ' || sec_num);
DBMS_OUTPUT.PUT_LINE('==================================');
OPEN S_NAME;
LOOP
FETCH S_NAME INTO fname , lname ;
EXIT WHEN S_NAME%notfound;
DBMS_OUTPUT.PUT_LINE(fname || ' ' || lname );
END LOOP;
CLOSE S_NAME ;
END LOOP;
CLOSE c_info;
END;
-- The output expected
-- I have having some issues, I am unable to display the proper output. I am trying to use a nested loop but i made some mistake when implementing it. Plus i think an explicit cursor is much better to be used.
Make use of the Northwood university database.
https://drive.google.com/file/d/1M_g7FbgOUahoFtE943OK28UxIFbUFgRk/view?usp=sharing
The script

Answer 1

I'm making a lot of assumptions here - I'm guessing you are getting all students for all courses in your inner loop, but you really just want get students for the particular course section you are dealing with in your outer loop.
So your second query will need to reference the right course section ID to limit the students to just that section.
You don't need to explicitly define cursors unless you need them for some reason - if you just iterating through them, its better to reference them directly in the FOR loop.
So that brings me to the following
set serveroutput on size 4000;
begin
for c_info in (
select call_id,
sec_num,
SEC_ID -- PK to link to enrollment later
from course_section,
course,
term
where course_section.course_id = course.course_id
and term.term_id = course_section.term_id
and term.term_desc = 'Summer 2007' ;
)
loop
dbms_output.put_line('==================================');
dbms_output.put_line(c_info.call_id || ' ' || 'Sec. ' || c_info.sec_num);
dbms_output.put_line('==================================');
for s_name in (
select distinct s_first, s_last
from student,
course_section,
term,
enrollment
where term.term_id = course_section.term_id
and course_section.c_sec_id = enrollment.c_sec_id
and course_section.term_id=term.term_id
and enrollment.s_id = student.s_id
and term.term_desc like 'Summer 2007'
AND ENROLLMENT.C_SEC_ID = C_INFO.SEC_ID -- get students just for THIS course section
)
loop
dbms_output.put_line(s_name.s_first || ' ' || s_name.s_last );
end loop;
end loop;
end;
where I've put query alterations in CAPS.
Since I cut/pasted your SQL there are no aliases in the first query - I'd recommend you correct that, as aliasing columns is always good practice.
Simiarly, I retained the DISTINCT in the second query, but I'd suspect its redundant, because I imagine a student wont enroll more than once for a single course section. (And in reality, if you had two different students named Sue Smith, you would probably want to print them out twice, no?)