SQL Exercise: List managers on lower salaries than their employees
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46. From the following table, write a SQL query to find those managers who receive less salary then the employees work under them. Return complete information about the employees.
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 | 2003-06-17 | AD_PRES | 24000.00 | 0.00 | 0 | 90 | | 101 | Neena | Kochhar | NKOCHHAR | 515.123.4568 | 2005-09-21 | AD_VP | 17000.00 | 0.00 | 100 | 90 | | 102 | Lex | De Haan | LDEHAAN | 515.123.4569 | 2001-01-13 | AD_VP | 17000.00 | 0.00 | 100 | 90 | | 103 | Alexander | Hunold | AHUNOLD | 590.423.4567 | 2006-01-03 | IT_PROG | 9000.00 | 0.00 | 102 | 60 | | 104 | Bruce | Ernst | BERNST | 590.423.4568 | 2007-05-21 | IT_PROG | 6000.00 | 0.00 | 103 | 60 | | 105 | David | Austin | DAUSTIN | 590.423.4569 | 2005-06-25 | IT_PROG | 4800.00 | 0.00 | 103 | 60 | | 106 | Valli | Pataballa | VPATABAL | 590.423.4560 | 2006-02-05 | IT_PROG | 4800.00 | 0.00 | 103 | 60 | | 107 | Diana | Lorentz | DLORENTZ | 590.423.5567 | 2007-02-07 | IT_PROG | 4200.00 | 0.00 | 103 | 60 | | 108 | Nancy | Greenberg | NGREENBE | 515.124.4569 | 2002-08-17 | FI_MGR | 12008.00 | 0.00 | 101 | 100 | | 109 | Daniel | Faviet | DFAVIET | 515.124.4169 | 2002-08-16 | FI_ACCOUNT | 9000.00 | 0.00 | 108 | 100 | ......... | 206 | William | Gietz | WGIETZ | 515.123.8181 | 2002-06-07 | AC_ACCOUNT | 8300.00 | 0.00 | 205 | 110 | +-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
Sample Solution:
SELECT *
FROM employees w
WHERE salary < ANY
(SELECT salary
FROM employees
WHERE w.emp_id=manager_id);
OR
SELECT DISTINCT m.emp_name,
m.salary
FROM employees w,
employees m
WHERE w.manager_id = m.emp_id
AND w.salary>m.salary;
OR
SELECT *
FROM employees w
WHERE emp_id IN
(SELECT manager_id
FROM employees
WHERE w.salary<salary);
Sample Output:
emp_id | emp_name | job_name | manager_id | hire_date | salary | commission | dep_id --------+----------+----------+------------+------------+---------+------------+-------- 65646 | JONAS | MANAGER | 68319 | 1991-04-02 | 2957.00 | | 2001 (1 row)
Explanation:
The said query in SQL that retrieves all employees from the employees table who have a salary lower than at least one of their managers.
The WHERE clause compares the salary of each employee with the salaries of their managers obtained from a subquery. The subquery that retrieves the salaries of all employees who have a manager with an emp_id equal to the manager_id of the employee.
The ANY operator in the subquery compares the salary of the employee with each of the salaries in the subquery.
Relational Algebra Expression:
Relational Algebra Tree:
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PREV : List the name of the managers with the most employees.
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Practice Online
Sample Database: employees
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