CREATE TABLE staffinfo (
emp_id INTEGER PRIMARY KEY,
emp_nm VARCHAR(50) NOT NULL,
birth_dt DATE NOT NULL,
start_dt DATE NOT NULL,
end_dt DATE
);
INSERT INTO staffinfo (emp_id, emp_nm, birth_dt, start_dt, end_dt) VALUES
(1, 'Ivanov', '1983-01-23', '2013-05-01', '2022-05-20'),
(2, 'Petrov', '1985-02-20', '2014-01-23', '2021-06-22'),
(3, 'Sidorov', '1980-04-01', '2015-05-05', NULL),
(4, 'Petrov', '2003-01-23', '2024-02-02', NULL),
(5, 'Vetrov', '2001-05-08', '2023-01-24', NULL);
select emp_id
from staffinfo
where emp_nm = 'Petrov'Â UNION end_dt is null;
Telegram: DB developers channel