CREATE OR REPLACE FUNCTION operator_check() RETURNS TRIGGER AS $$
DECLARE
    curDate TIMESTAMP;
    curDuration INTERVAL;
BEGIN
    FOR curDate, curDuration IN
    (SELECT start_time, duration FROM Shoots
        WHERE oid=NEW.oid AND
        start_time > current_timestamp - interval '1 day') LOOP
            IF (SELECT (NEW.start_time, NEW.duration) OVERLAPS (curDate, curDuration))
            THEN
                RAISE EXCEPTION 'Operator is busy at %-%', curDate, curDate + curDuration;
            END IF;
        RETURN NEW;
    END LOOP;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION journalist_check() RETURNS TRIGGER AS $$
DECLARE
    curDate TIMESTAMP;
    curDuration INTERVAL;
BEGIN
    FOR curDate, curDuration IN
    (SELECT start_time, duration FROM Shoots
        WHERE jid=NEW.jid AND
        start_time > current_timestamp - interval '1 day') LOOP
            IF (SELECT (NEW.start_time, NEW.duration) OVERLAPS (curDate, curDuration))
            THEN
                RAISE EXCEPTION 'Journalist is busy at %-%', curDate, curDate + curDuration;
            END IF;
        RETURN NEW;
    END LOOP;
END;
$$ LANGUAGE plpgsql;