如果日期已过

Question

任何人都知道如何检查日期是否过去了。我的数据库中有一个返回日期列，它是一个将来的日期，当该日期过去时，我需要在触发器中包含此日期以提醒经理。我已经尝试过此代码，但无法正常工作。

DELIMITER //
CREATE TRIGGER date_expired BEFORE INSERT ON external_requests
FOR EACH ROW 
BEGIN 
IF return_date >= (return_date) Then 
SIGNAL SQLSTATE '45000' set message_text='This book has not been returned to the library';

END//
DELIMITER ;

Answer 1

您要寻找curdate()吗？

DELIMITER //
CREATE TRIGGER date_expired BEFORE INSERT ON external_requests
FOR EACH ROW 
BEGIN 
    IF return_date >= curdate() Then 
        SIGNAL SQLSTATE '45000' 
               set message_text='This book has not been returned to the library';
    end if;

END//
DELIMITER ;