SQLite Online

DROP TABLE IF EXISTS employees;

CREATE TABLE employees( id          integer,  name    text,
                        designation text,     manager integer,
                        hired_on    date,     salary  integer);

INSERT INTO employees VALUES ( 1, 'JOHNSON',    'ADMIN',       6, '1990-12-17', 18000);
INSERT INTO employees VALUES ( 2, 'HARDING',    'MANAGER',     9, '1998-02-02', 52000);
INSERT INTO employees VALUES ( 3, 'TAFT',       'SALES I',     2, '1996-01-02', 25000);
INSERT INTO employees VALUES ( 4, 'HOOVER',     'SALES I',     2, '1990-04-02', 27000);
INSERT INTO employees VALUES ( 5, 'LINCOLN',    'TECH',        6, '1994-06-23', 22500);
INSERT INTO employees VALUES ( 6, 'GARFIELD',   'MANAGER',     9, '1993-05-01', 54000);
INSERT INTO employees VALUES ( 7, 'POLK',       'TECH',        6, '1997-09-22', 25000);
INSERT INTO employees VALUES ( 8, 'GRANT',      'ENGINEER',   10, '1997-03-30', 32000);
INSERT INTO employees VALUES ( 9, 'JACKSON',    'CEO',      NULL, '1990-01-01', 75000);
INSERT INTO employees VALUES (10, 'FILLMORE',   'MANAGER',     9, '1994-08-09', 56000);
INSERT INTO employees VALUES (11, 'ADAMS',      'ENGINEER',   10, '1996-03-15', 34000);
INSERT INTO employees VALUES (12, 'WASHINGTON', 'ADMIN',       6, '1998-04-16', 18000);
INSERT INTO employees VALUES (13, 'MONROE',     'ENGINEER',   10, '2000-12-03', 30000);
INSERT INTO employees VALUES (14, 'ROOSEVELT',  'CPA',         9, '1995-10-12', 35000);

SELECT designation, COUNT(*) AS nbr, (AVG(salary)) AS avg_salary FROM employees GROUP BY designation ORDER BY avg_salary DESC;
SELECT name, hired_on FROM employees ORDER BY hired_on;
Results