How do I write a program where it shows the average of the average for students whose age are 20 or below. Using (for loop) in Oracle SQL Developer

Question

Basically I need to use (for loop) in Oracle SQL Developer to show the average of the average for students whose age is 20 or below. Down Below is the students' table

question from:https://stackoverflow.com/questions/65917179/how-do-i-write-a-program-where-it-shows-the-average-of-the-average-for-students

Answer 1

I guess it is a homework (funny requirements for simple situations). Anyway, see if something like this helps.

SQL> set serveroutput on
SQL>
SQL> declare
  2    l_avg number;
  3    l_sum number := 0;
  4    l_cnt number := 0;
  5  begin
  6    for cur_r in (select avg from test where age <= 20) loop
  7      l_cnt := l_cnt + 1;
  8      l_sum := l_sum + cur_r.avg;
  9    end loop;
 10
 11    if l_cnt > 0 then
 12       l_avg := l_sum / l_cnt;
 13    end if;
 14
 15    dbms_output.put_line('Average is ' || nvl(to_char(l_avg), 'unknown'));
 16  end;
 17  /
Average is 68

PL/SQL procedure successfully completed.

SQL>