SQL exercises on employee Database: Display the number of employee for each job in each department

SQL employee Database: Exercise-97 with Solution

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97. From the following table, write a SQL query to count the number of employees of each designation in each department. Return department id, job name and number of employees.

Sample table: employees

Sample Solution:

SELECT dep_id,
       job_name,
       count(*)
FROM employees
GROUP BY dep_id,
         job_name;

Sample Output:

 dep_id | job_name  | count
--------+-----------+-------
   3001 | MANAGER   |     1
   2001 | ANALYST   |     2
   3001 | SALESMAN  |     4
   1001 | MANAGER   |     1
   1001 | PRESIDENT |     1
   2001 | MANAGER   |     1
   2001 | CLERK     |     2
   1001 | CLERK     |     1
   3001 | CLERK     |     1
(9 rows)

Relational Algebra Expression:

Relational Algebra Tree:

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Sample Database: employee

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Previous: From the following table, write a SQL query to list the managers and number of employees work under them. Sort the result set in ascending order on manager. Return manager ID and number of employees under them.
Next: From the following table, write a SQL query to find those departments where at least two employees work. Return department id, number of employees.