MySQL的触发

Question

之前，我有这两个表：

CREATE TABLE `reservation` (
    `id_reservation` int(11) PRIMARY KEY, 
    `reserved_date` date NOT NULL, 
    `id_event` int(11) NOT NULL, 
    FOREIGN KEY (`id_event`) REFERENCES `event` 
    ) 

    CREATE TABLE `event` (
    `id_event` int(11) PRIMARY KEY, 
    `begin_date` date NOT NULL, 
    `end_date` date NOT NULL, 
    ) 

基本上我插入reservation具有单reserved_date。 reservation与event有关，其具有begin_date和end_date。

我需要检查reserved_date包含（Y < = X < = Z）在begin_date和该特定event的end_date。

Answer 1

试试这个触发器 -

CREATE TRIGGER trigger1 
    BEFORE INSERT 
    ON reservation 
    FOR EACH ROW 
BEGIN 
    DECLARE id_event_var INT DEFAULT NULL; 
    SELECT id_event INTO id_event_var FROM `event` WHERE id_event = new.id_event AND new.reserved_date >= begin_date AND new.reserved_date <= end_date; 
    IF id_event_var IS NULL THEN 
    ... -- wrong date! 
    END IF; 
END