declare
 v_row1 number;
 v_row2 number;
 v_row3 number;
 cursor c1 is
 select deptno, sum(sal) sl
 from emp
 group by deptno;
 c2 c1%rowtype;
 begin
  open c1;
  loop fetch c1 into c2;
  exit when c1%notfound;
   if c1%rowcount = 1 then
    v_row1 := c2.sl;
   end if;
   if c1%rowcount = 2 then
    v_row2 := c2.sl;
   end if;
   if c1%rowcount = 3 then
    v_row3 := c2.sl;
   end if;
 --  dbms_output.put_line(v_row1);
 --  dbms_output.put_line(v_row2);
 --  dbms_output.put_line(v_row3);
   dbms_output.put_line(c1%rowcount||' '||c2.sl);
  end loop;
 close c1;
 end;

1 8750
2 10875
3 9400

BEGIN
  FOR cur_r IN (SELECT deptno, SUM(sal) s1
                FROM EMP
                GROUP BY deptno
               )
  LOOP
    dbms_output.put_line(cur_r.deptno ||' '|| cur_r.s1);
  END LOOP;
END;
/

30 9400
20 10875
10 8750

PL/SQL procedure successfully completed.

SQL> create table t
  2  (col1 number,
  3   col2 number,
  4   col3 number)
  5  /

Table created.

After running the code the values should be populated in my table like this

SQL> select * from t;

      COL1       COL2       COL3
---------- ---------- ----------
      8750      10875       9400

INSERT INTO t 
  (COL1, COL2, COL3)
   VALUES 
  ((SELECT SUM(sal) FROM EMP WHERE deptno = 10),
   (SELECT SUM(sal) FROM EMP WHERE deptno = 20),
   (SELECT SUM(sal) FROM EMP WHERE deptno = 30)
  );

DECLARE
  l_cnt NUMBER := 1;
BEGIN
  FOR cur_r IN (SELECT deptno, SUM(sal) s1
                FROM EMP
                GROUP BY deptno
		ORDER BY deptno
               )
  LOOP
    IF l_cnt = 1 THEN
       INSERT INTO t (col1) VALUES (cur_r.s1);
    ELSIF l_cnt = 2 THEN
       UPDATE t SET col2 = cur_r.s1;
    ELSIF l_cnt = 3 THEN
       UPDATE t SET col3 = cur_r.s1;
    END IF;
				
    l_cnt := l_cnt + 1;
  END LOOP;
END;
/