Still training, lab fails.

Question

Here's the outline: ( code below)
a)Accept a number n from the user where n represents the number of top n earners from the employees table. For example, to view the top five salaries, enter 5. (Note: Use the DEFINE command to define a variable p_num to provide the value for n. Pass the value to the PL/SQL block through an iSQL*Plus substitution variable.)
SET SERVEROUTPUT ON
SET VERIFY OFF
DECLARE
num NUMBER(3) := &p_num;
sal employees.salary&TYPE;
CURSOR emp_cursor IS
SELECT distinct salary
FROM employees
ORDER BY salary DESC;
BEGIN
OPEN emp_cursor;
FETCH emp_cursor INTO sal;
WHILE emp_cursor%ROWCOUNT <= num AND emp_cursor%FOUND LOOP
     INSERT INTO top_salaries (salary)
     VALUES (sal);
FETCH emp_cursor INTO sal;
END LOOP;
CLOSE emp_cursor;
COMMIT;
END;
SELECT * FROM top_salaries:
Which generates a lot of errors:
Enter value for type: 0
sal employees.salary0;
ERROR at line 4:
ORA-06550: line 4, column 15:
PLS-00302: component 'SALARY0' must be declared
ORA-06550: line 4, column 5:
PL/SQL: Item ignored
ORA-06550: line 13, column 24:
PLS-00320: the declaration of the type of this expression is incomplete or
malformed
ORA-06550: line 13, column 2:
PL/SQL: SQL Statement ignored
ORA-06550: line 16, column 10:
PLS-00320: the declaration of the type of this expression is incomplete or
malformed
ORA-06550: line 16, column 10:
PL/SQL: ORA-00904: "SAL": invalid identifier
ORA-06550: line 15, column 2:
PL/SQL: SQL Statement ignored
ORA-06550: line 17, column 24:
PLS-00320: the declaration of the type of this expression is incomplete or
malformed
ORA-06550: line 17, column 2:
PL/SQL: SQL Statement ignored
I can not see the problem, I have been looking at it too long.

Answer 1

Firstly my query and yours fetches totally different result
SQL> select sal from emp order by sal desc
  2  /
       SAL
      5000
      3000
      3000
      2975
      2850
      2450
      1600
      1500
      1300
      1250
      1250
       SAL
      1100
       950
       800
14 rows selected.
SQL> SELECT   sal
  2  FROM   (  SELECT   sal
  3         FROM   emp
  4     ORDER BY   sal DESC)
  5  WHERE   ROWNUM <= &num
  6  /
Enter value for num: 5
old   5: WHERE   ROWNUM <= &num
new   5: WHERE   ROWNUM <= 5
       SAL
      5000
      3000
      3000
      2975
      2850
SQL> select distinct sal
  2    from (select sal, dense_rank() over(order by sal desc) rnk
  3       from emp)
  4   where rnk <= &rank
  5  /
Enter value for rank: 5
old   4:  where rnk <= &rank
new   4:  where rnk <= 5
       SAL
      5000
      3000
      2975
      2850
      2450Just by seeing users code i believe he wants TOP DISTINCT salary.
And secondly why do you do this
EXCEPTION
   WHEN OTHERS
   THEN
      ROLLBACK;
      DBMS_OUTPUT.put_line (SQLERRM);
      RAISE;You are suppressing an nice error. Why don't you just let it go?