For each dept_id (including the employees with no department as their own group), show avg_salary rounded to 0 decimals.
6 rows with columns dept_id, avg_salary — first 3 shown:
| # | ||
|---|---|---|
| 1 | NULL | 90000 |
| 2 | 1 | 127143 |
| 3 | 2 | 85000 |
Run your code to see the output here.