SQL Exercise: Display details and experience of all the managers
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2. From the following table, write a SQL query to compute the experience of all the managers. Return employee ID, employee name, job name, joining date, and experience.
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 emp_id,
emp_name,
job_name,
hire_date,
age(CURRENT_DATE, hire_date) "Experience"
FROM employees
WHERE emp_id IN
(SELECT manager_id
FROM employees);
Sample Output:
emp_id | emp_name | job_name | hire_date | Experience --------+----------+-----------+------------+------------------------- 68319 | KAYLING | PRESIDENT | 1991-11-18 | 26 years 2 mons 17 days 66928 | BLAZE | MANAGER | 1991-05-01 | 26 years 9 mons 4 days 67832 | CLARE | MANAGER | 1991-06-09 | 26 years 7 mons 26 days 65646 | JONAS | MANAGER | 1991-04-02 | 26 years 10 mons 3 days 67858 | SCARLET | ANALYST | 1997-04-19 | 20 years 9 mons 16 days 69062 | FRANK | ANALYST | 1991-12-03 | 26 years 2 mons 2 days (6 rows)
Explanation:
The given query in SQL that returns a table of information about employees who are also managers, including their ID, name, job name, hire date, and experience from the 'employees' table.
The CURRENT_DATE function calculates the "Experience" as the difference between the current date and the "hire_date" of each employee.
The WHERE clause only includes those employees in the result set who are managers.
Alternative Solution:
Using EXISTS:
-- Selecting employee details for those who have a manager
SELECT emp_id,
emp_name,
job_name,
hire_date,
age(CURRENT_DATE, hire_date) AS "Experience"
FROM employees e
WHERE EXISTS
(
-- Subquery checks if there is at least one record
-- in the "employees" table where the manager_id
-- matches the emp_id of the outer query's employee
SELECT 1
FROM employees
WHERE manager_id = e.emp_id
);
Explanation:
The EXISTS subquery is used to check if there exists a record in the employees table where the manager_id matches the emp_id of the outer query's employee, filtering the results accordingly.
Go to:
PREV : Display all the details of managers.
NEXT : Display the list in ascending order of location.
Practice Online
Sample Database: employees
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