Question

我有一个具有这种结构的数据库：

用户
- ID
- 用户名
- ........
- user_status
问题
- ID
- asker_id
- asked_id
- ........
- question_status
答案
- ID
- question_id
- who_answer_id
- ........
- answer_status
喜欢
- ID
- liker_id
- liked_id
- ........
- like_status

如何更新user_status =＆＃39;已删除＆＃39;自动设置：

question_status = deleted
answer_status = deleted
like_status = deleted

Answer 1

假设您正在使用SQL服务器（因为我看不到指定的数据库），我会说对表用户执行1次触发，如下所示（可能不准确）

CREATE TRIGGER [user_statusDeleted]
ON [users]
After UPDATE, INSERT --INSERT may not be relevant
AS 
BEGIN
UPDATE q
SET q.[question_status] = deleted
FROM [inserted] i 
    JOIN [questions] q
        ON i.[Id] = q.[asker_id] --or asked_id ?
        AND i.[user_status] = deleted

然后在表格之后再添加两个表格答案和喜欢的更新（抱歉，无论如何我会猜测连接），用分号分隔，它应该可以工作。

更多关于sql server中的触发器 - https://msdn.microsoft.com/en-us/library/ms189799.aspx

Answer 2

这个触发器有什么作用？

列表项
定义新触发器
检查user_status列是否已更新。
检查user_status是否已更新为＆＃39;已删除＆＃39;
记录该用户的ID，并更改其所有问题，答案和喜欢的状态以删除＆＃39;。

代码：

DELIMITER //
CREATE TRIGGER  user_delete BEFORE UPDATE ON users FOR EACH ROW
BEGIN
    IF NEW.user_status <> OLD.user_status
    THEN 
        IF STRCMP('deleted',NEW.user_status) = 0 THEN
            UPDATE question_status SET question_status = 'deleted' WHERE asker_id = NEW.id;
            UPDATE answers SET answer_status = 'deleted' WHERE who_answer_id = NEW.id;
            UPDATE likes SET like_status = 'deleted' WHERE liker_id = NEW.id;
        END IF;
        IF STRCMP('active',NEW.user_status) = 0 THEN
            UPDATE question_status SET question_status = 'active' WHERE asker_id = NEW.id;
            UPDATE answers SET answer_status = 'active' WHERE who_answer_id = NEW.id;
            UPDATE likes SET like_status = 'active' WHERE liker_id = NEW.id;
        END IF;
    END IF;
END//
DELIMITER ;

您稍后可能会注意到的可能流程

只需在您的网站上考虑这种情况，QuestionA已被删除＆＃39;一些主持人，现在当用户（这个问题的海报）被重新激活时，所有这些主持的问题/答案都会回来！

理想情况下，您应该有另一种状态来决定是自动删除还是手动删除。也许＆＃39; auto_delete＆＃39;并且＆＃39;删除＆＃39;而不只是使用＆＃39;删除＆＃39;。

Answer 3

BEGIN
    IF NEW.user_status <> OLD.user_status
    THEN 
        IF STRCMP('deleted',NEW.user_status) = 0 THEN
            UPDATE questions SET question_status = 'deleted' WHERE asker_id = NEW.id AND question_status != 'mod_deleted';
            UPDATE answers SET answer_status = 'deleted' WHERE commentator_id = NEW.id AND answer_status != 'mod_deleted';
            UPDATE likes SET like_status = 'deleted' WHERE liker_id = NEW.id AND like_status != 'mod_deleted';
        END IF;
        IF STRCMP('active',NEW.user_status) = 0 THEN
            UPDATE questions SET question_status = 'active' WHERE asker_id = NEW.id AND question_status != 'mod_deleted';
            UPDATE answers SET answer_status = 'active' WHERE commentator_id = NEW.id AND answer_status != 'mod_deleted';
            UPDATE likes SET like_status = 'active' WHERE liker_id = NEW.id AND like_status != 'mod_deleted';
        END IF;
    END IF;
END

_status字段是枚举类型，所以如果我添加mod_deleted并在更新中添加一个AND应该解决流程

数据库多表触发

3 个答案: