PostgreSQL JOINS: Make a join with tables employees and departments to get the department name and number of employees working in each department
6. Write a query to make a join with two tables employees and departments to get the department name and number of employees working in each department.
Sample Solution:
Code:
SELECT department_name AS "Department Name",
COUNT(*) AS "No of Employees"
FROM departments
INNER JOIN employees
ON employees.department_id = departments.department_id
GROUP BY departments.department_id, department_name
ORDER BY department_name;
Sample table: employees
Sample table: departments
Output:
pg_exercises=# SELECT department_name AS "Department Name", pg_exercises-# COUNT(*) AS "No of Employees" pg_exercises-# FROM departments pg_exercises-# INNER JOIN employees pg_exercises-# ON employees.department_id = departments.department_id pg_exercises-# GROUP BY departments.department_id, department_name pg_exercises-# ORDER BY department_name; Department Name | No of Employees ------------------+----------------- Accounting | 2 Administration | 1 Executive | 3 Finance | 6 Human Resources | 1 IT | 5 Marketing | 2 Public Relations | 1 Purchasing | 6 Sales | 33 Shipping | 45 (11 rows)
Practice Online
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Previous: Write a query to make a join with a table employees and itself to find the name, including first_name and last_name and hire date for those employees who were hired after the employee Jones.
Next: Write a query to make a join to find the employee ID, job title and number of days an employee worked, for all the employees who worked in a department which ID is 90.
What is the difficulty level of this exercise?
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