INSERT INTO employee (id, first_name, last_name, login, password)
 SELECT 1, 'Adam', 'Gąsiorek', 'adacho', 'adam123' FROM dual UNION ALL
 SELECT 2, 'Dominik', 'Gądek', 'dominic', 'dominik123' FROM dual UNION ALL
 SELECT 3, 'Maksym', 'Gilewski', 'reage', 'maksym123' FROM dual;