Couple of Oracle SQL Questions

Hello,
Really Struggling on a couple of things with Oracle and was wondering if anybody here could help me.

First of all I have the following statement:

SELECT ename
FROM emp 
WHERE job  NOT IN ('CLERK', 'ANALYST', 'SALESMAN');

Code (markup):

I need to think of another way to perform the same function, which is to give details of all employees who are not Clerks, Analysts or Salesment. I tried to have a mess around with NOT EXIST but just cannot get anything to work.

Secondly I am trying to show a list of courses which no students are enrolled on. I thought the following may work

SELECT COURSENAME AS Coursename
FROM COURSE
INNER JOIN STUDENT
ON course.coursename = student.coursename
GROUP BY coursename
HAVING count(coursecode) >= 1;

Code (markup):

However that is not working I am getting the error

I did try another way which ended up with it just displaying all the courses whatever number I changed the count to.

Any ideas?

 

You could just do:
WHERE job <> 'CLERK'
AND job <> 'ANALYST'
etc...

It's uglier but is the same function.

On the second, I would first double check that coursename is a valid column in the student table.

Secondly, I would explicitly specify which coursename you are referring to in the query. It's ambiguous all over the place as to which coursename you mean.

Should be:

SELECT course.coursename AS Coursename 
FROM   course 
       inner join student 
               ON course.coursename = student.coursename 
GROUP  BY course.coursename 
HAVING Count(course.coursecode) >= 1; 

Code (markup):

 

Thank you very much! Managed to work it out with a bit of tweaking.

You have been a great help!