在触发程序中使用IF陈述式，检查您是否要将vacation从0变更为1。如果是，请将间隔加入employee_table中的date_nastne数据行。

CREATE TRIGGER AFTER UPDATE ON przykladowa
FOR EACH ROW
IF NEW.vacation = 1 AND OLD.vacation = 0
THEN
    UPDATE employee_table
    set date_nastne = date_nastne + INTERVAL NEW.interval DAY
    where added = 1;
END IF;