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Write a query in SQL to list the department where there are no employees

Write a query in SQL to list the department where there are no employees


 Write a query in SQL to list the department where there are no employees.

 

Sample table: employees

emp_id | emp_name | job_name  | manager_id | hire_date  | salary  | commission | dep_id
--------+----------+-----------+------------+------------+---------+------------+--------
  68319 | KAYLING  | PRESIDENT |            | 1991-11-18 | 6000.00 |            |   1001
  66928 | BLAZE    | MANAGER   |      68319 | 1991-05-01 | 2750.00 |            |   3001
  67832 | CLARE    | MANAGER   |      68319 | 1991-06-09 | 2550.00 |            |   1001
  65646 | JONAS    | MANAGER   |      68319 | 1991-04-02 | 2957.00 |            |   2001
  67858 | SCARLET  | ANALYST   |      65646 | 1997-04-19 | 3100.00 |            |   2001
  69062 | FRANK    | ANALYST   |      65646 | 1991-12-03 | 3100.00 |            |   2001
  63679 | SANDRINE | CLERK     |      69062 | 1990-12-18 |  900.00 |            |   2001
  64989 | ADELYN   | SALESMAN  |      66928 | 1991-02-20 | 1700.00 |     400.00 |   3001
  65271 | WADE     | SALESMAN  |      66928 | 1991-02-22 | 1350.00 |     600.00 |   3001
  66564 | MADDEN   | SALESMAN  |      66928 | 1991-09-28 | 1350.00 |    1500.00 |   3001
  68454 | TUCKER   | SALESMAN  |      66928 | 1991-09-08 | 1600.00 |       0.00 |   3001
  68736 | ADNRES   | CLERK     |      67858 | 1997-05-23 | 1200.00 |            |   2001
  69000 | JULIUS   | CLERK     |      66928 | 1991-12-03 | 1050.00 |            |   3001
  69324 | MARKER   | CLERK     |      67832 | 1992-01-23 | 1400.00 |            |   1001
(14 rows)
 dep_id |  dep_name  | dep_location
--------+------------+--------------
   1001 | FINANCE    | SYDNEY
   2001 | AUDIT      | MELBOURNE
   3001 | MARKETING  | PERTH
   4001 | PRODUCTION | BRISBANE
(4 rows)

الأجوبة

SELECT b.dep_id,
       count(a.dep_id)
FROM department b
LEFT OUTER JOIN employees a ON a.dep_id=b.dep_id
GROUP BY b.dep_id
HAVING count(a.dep_id) = 0;

Sample Output:

 dep_id | count
--------+-------
   4001 |     0
(1 row)
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