List the name of division that all employees are working on some project(s) - sql

Question

List the name of division that ALL employees are working on some project(s). Namly, there not exists an employee who do is the full question. I'm having trouble getting an actual answer for this one, and my professor is being no help to telling me what I'm doing wrong. The code I have is
select dname
from division d, employee e, workon w
where e.did = d.did
and w.empid = e.empid
and not exists
(select empid
from workon
group by empid
having count (empid) >= all(select e.empid
from employee ee
where e.did = ee.did
group by ee.empid))
group by dname
The tables I have are
Employee
| EMPID | NAME | SALARY | DID |
--------------------------------
| 1 | kevin | 32000 | 2 |
| 2 | joan | 46200 | 1 |
| 3 | brian | 37000 | 3 |
| 4 | larry | 82000 | 5 |
| 5 | harry | 92000 | 4 |
| 6 | peter | 45000 | 2 |
| 7 | peter | 68000 | 3 |
| 8 | smith | 39000 | 4 |
| 9 | chen | 71000 | 1 |
| 10 | kim | 46000 | 5 |
Division
| DID | DNAME | MANAGERID |
----------------------------------------------
| 1 | engineering | 2 |
| 2 | marketing | 1 |
| 3 | human resource | 3 |
| 4 | Research and development | 5 |
| 5 | accounting | 4 |
Workon
| PID | EMPID | HOURS |
-----------------------
| 3 | 1 | 30 |
| 2 | 3 | 40 |
| 5 | 4 | 30 |
| 6 | 6 | 60 |
| 4 | 3 | 70 |
| 2 | 4 | 45 |
| 5 | 3 | 90 |
| 3 | 3 | 100 |
| 6 | 8 | 30 |
| 4 | 4 | 30 |
| 5 | 8 | 30 |
| 6 | 7 | 30 |
| 6 | 9 | 40 |
| 5 | 9 | 50 |
| 4 | 6 | 45 |
| 2 | 7 | 30 |
| 2 | 8 | 30 |
| 2 | 9 | 30 |
| 1 | 9 | 30 |
| 1 | 8 | 30 |
| 1 | 7 | 30 |
| 1 | 5 | 30 |
| 1 | 6 | 30 |
| 2 | 6 | 30 |

Answer 1

You're very close. What you're trying to do is called a "correlated subquery". You're relating a key from a table you are querying to a key in a query that doesn't contribute to the candidate set, but does act as a filter in your where clause.
The key line in your code that demonstrates this is the line in the NOT EXISTS clause that says:
e.did = ee.did
Instead of trying to do this by comparing aggregate COUNT(...) results, do an outer join between the Employee and Workon tables to find out if there are any employees who aren't doing anything, then find your departments based on those employees not existing for a given department.
Here's an example query using the Oracle standard HR example tutorial tables representing the same join conditions as you have here. You probably have access to these tables wherever you're running the query, and so should anyone else here who might be interested in the answer, so they can run the query without building your tables to play around with the answer. It's a relatively trivial matter to convert the query to your tables, so I'll leave that exercise to you! :)
The final capitalized line in my query below is the join condition that makes this query a correlated subquery, like you tried to do in yours.
select
*
from
hr.departments d
where
not exists
(
select
ee.employee_id
,ee.first_name
,ee.last_name
,dd.department_id
,dd.department_name
,jj.job_id
from
hr.employees ee
,hr.departments dd
,hr.job_history jj
where
ee.department_id = dd.department_id
and ee.employee_id = jj.employee_id (+)
and jj.job_id is null
AND D.DEPARTMENT_ID = DD.DEPARTMENT_ID
)