SQL Exercise: Number of employees equals to department length

SQL subqueries on employee Database: Exercise-41 with Solution

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41. From the following tables, write a SQL query to find those departments where the number of employees is equal to the number of characters in the department name. Return complete information about the employees.

Sample table: employees

Sample table: department

Sample Solution:

SELECT *
FROM department d
WHERE length(dep_name) IN
    (SELECT count(*)
     FROM employees e
     WHERE e.dep_id = d.dep_id );

OR

SELECT d.dep_name,
       count(*)
FROM employees e,
     department d
WHERE e.dep_id = d.dep_id
GROUP BY d.dep_name
HAVING count(*) = LENGTH (d.dep_name);

Sample Output:

 dep_id | dep_name | dep_location
--------+----------+--------------
   2001 | AUDIT    | MELBOURNE
(1 row)

Explanation:

The said query in SQL that selects all departments from the departments table where the length of the department name is equal to the number of employees in that department.

The WHERE clause filters the results to only include departments where the length of the dep_name is equal to the number of employees in that department.

The inner query is a subquery that returns the count of employees for each department.

The IN operator is used to compare the result of the subquery to the length of the department name in the outer query.

Practice Online

Structure of employee DataBase:

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