Mysql 触发器与 IF THEN
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Mysql Trigger with IF THEN
提问by Alex Prut
My storage is INNODB, I'm trying to create an trigger with 2 queries in IF statement. Down you can see the trigger that gives me the error
我的存储是 INNODB，我试图在 IF 语句中创建一个带有 2 个查询的触发器。向下你可以看到给我错误的触发器
delimiter |
CREATE TRIGGER count_delete_videos BEFORE DELETE ON videos
FOR EACH ROW BEGIN
UPDATE counts SET count = count - 1 WHERE name = 'all';
IF OLD.published = 1 THEN
DELETE FROM videos_categories WHERE id_video = OLD.id;
DELETE FROM videos_tags WHERE id_video = OLD.id;
END IF;
END;
|
delimiter ;
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= OLD.id;
END IF;
END' at line 6
This are the 2 triggers that i activate with the first one.
这是我用第一个激活的 2 个触发器。
delimiter |
CREATE TRIGGER count_delete_videos_tags AFTER DELETE ON videos_tags
FOR EACH ROW BEGIN
UPDATE tags SET count = count - 1 WHERE id = OLD.id_tag;
END;
|
delimiter ;
delimiter |
CREATE TRIGGER count_delete_videos_categories AFTER DELETE ON videos_categories
FOR EACH ROW BEGIN
UPDATE categories SET count = count - 1 WHERE id = OLD.id_category;
IF OLD.id_category <> 20 AND OLD.id_category <> 34 THEN
UPDATE counts SET count=count-1 WHERE name='english';
ELSEIF OLD.id_category = 34 THEN
UPDATE counts SET count=count-1 WHERE name='german';
ELSEIF OLD.id_category = 20 THEN
UPDATE counts SET count=count-1 WHERE name='italian';
END IF;
END;
|
delimiter ;
But this one works perfectly
但这个完美地工作
delimiter |
CREATE TRIGGER count_delete_videos BEFORE DELETE ON videos
FOR EACH ROW BEGIN
UPDATE counts SET count = count - 1 WHERE name = 'all';
IF OLD.published = 1 THEN
DELETE FROM videos_categories WHERE id_video = OLD.id;
END IF;
END;
|
delimiter ;
Query OK, 0 rows affected (0.16 sec)
How can i make first trigger work? what i'm doing wrong? Thx for helping me.
我怎样才能使第一个触发器工作？我做错了什么？感谢帮助我。
回答by Johan
As far as I can tell both triggers are OK, but you might try the following:
据我所知，两个触发器都可以，但您可以尝试以下操作：
DELIMITER $$
CREATE TRIGGER count_delete_videos BEFORE DELETE ON videos
FOR EACH ROW
BEGIN
UPDATE counts SET count = count - 1 WHERE name = 'all';
IF OLD.published = 1 THEN BEGIN
DELETE FROM videos_categories WHERE id_video = OLD.id;
DELETE FROM videos_tags WHERE id_video = OLD.id;
END; END IF;
END$$
DELIMITER ;
