SQLite Exercise: List the number of jobs available in the employees table

Write a query to list the number of jobs available in the employees table.

Sample table : employees

+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
| EMPLOYEE_ID | FIRST_NAME  | LAST_NAME   | EMAIL    | PHONE_NUMBER       | HIRE_DATE  | JOB_ID     | SALARY   | COMMISSION_PCT | MANAGER_ID | DEPARTMENT_ID |
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
|         100 | Steven      | King        | SKING    | 515.123.4567       | 1987-06-17 | AD_PRES    | 24000.00 |           0.00 |          0 | 		  90 |
|         101 | Neena       | Kochhar     | NKOCHHAR | 515.123.4568       | 1987-06-18 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         102 | Lex         | De Haan     | LDEHAAN  | 515.123.4569       | 1987-06-19 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         103 | Alexander   | Hunold      | AHUNOLD  | 590.423.4567       | 1987-06-20 | IT_PROG    |  9000.00 |           0.00 |        102 |            60 |
|         104 | Bruce       | Ernst       | BERNST   | 590.423.4568       | 1987-06-21 | IT_PROG    |  6000.00 |           0.00 |        103 |            60 |
|         105 | David       | Austin      | DAUSTIN  | 590.423.4569       | 1987-06-22 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         106 | Valli       | Pataballa   | VPATABAL | 590.423.4560       | 1987-06-23 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         107 | Diana       | Lorentz     | DLORENTZ | 590.423.5567       | 1987-06-24 | IT_PROG    |  4200.00 |           0.00 |        103 |            60 |
|         108 | Nancy       | Greenberg   | NGREENBE | 515.124.4569       | 1987-06-25 | FI_MGR     | 12000.00 |           0.00 |        101 |           100 |
|         109 | Daniel      | Faviet      | DFAVIET  | 515.124.4169       | 1987-06-26 | FI_ACCOUNT |  9000.00 |           0.00 |        108 |           100 |
...........
|         206 | William     | Gietz       | WGIETZ   | 515.123.8181       | 1987-10-01 | AC_ACCOUNT |  8300.00 |           0.00 |        205 |           110 |
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+

View the table

SQLite Code :

-- Counting the number of distinct job IDs in the "job_id" column
SELECT COUNT(DISTINCT job_id) 
-- Specifying the table from which to retrieve the data, in this case, "employees"
FROM employees;

Output:

COUNT(DISTINCT job_id)
----------------------
19

Explanation:

The above SQLite query counts the number of distinct job IDs in the "employees" table. The result is a single value representing the count of unique job IDs.

Here's a brief explanation of each part of SQLite code:

• SELECT clause:
• It uses the COUNT function to count the number of distinct values in the "job_id" column of the "employees" table.
• FROM clause:
• Specifies the table from which to retrieve the data, in this case, the "employees" table.
• DISTINCT keyword:
• The DISTINCT keyword is used with the COUNT function to ensure that only unique (distinct) values of "job_id" are considered in counting.

Relational Algebra Expression:

Relational Algebra Tree:

Go to:

• SQLite Aggregate Functions and Group by Exercises Home. ↩
• SQLite Exercises Home ↩

PREV : Aggregate Functions and Group by
NEXT : Write a query to get the total salaries payable to employees.

Practice SQLite Online

Model Database

Structure of 'hr' database :

Improve this sample solution and post your code through Disqus.