SQLite Exercise: Find the names of the employees who are managers
Write a query to find the names (first_name, last_name) of the employees who are managers.
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 | +-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
SQLite Code:
-- Selecting the first name and last name of employees
SELECT first_name, last_name
-- Specifying the table from which to retrieve the data, in this case, "employees"
FROM employees
-- Filtering the results to include only rows where the employee_id is in a subquery result
WHERE (employee_id IN (SELECT manager_id FROM employees));
Output:
first_name last_name ---------- ---------- Steven King Neena Kochhar Lex De Haan Alexander Hunold Nancy Greenberg ... ... Alberto Errazuriz Gerald Cambrault Eleni Zlotkey Michael Hartstein Shelley Higgins
Explanation:
The above SQLite query selects the first name and last name of employees from the "employees" table, including only those employees who are also managers. The subquery finds 'manager_id' values within the same "employees" table, and the main query filters employees based on whether their employee_id is in the list of 'manager_id' values.
Here's a brief explanation of each part of SQLite code:
- SELECT clause:
- It selects the "first_name" and "last_name" columns.
- FROM clause:
- Specifies the table from which to retrieve the data, in this case, the "employees" table.
- WHERE clause:
- Filters the results to include only rows where "employee_id" is in a subquery result.
- Subquery:
- The subquery (SELECT manager_id FROM employees) retrieves the "manager_id" values from the same "employees" table.
- This subquery is used in the WHERE clause to filter employees based on whether their "employee_id" is also present in the "manager_id" values.
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Practice SQLite Online
Model Database
Structure of 'hr' database :
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