php - MySQL 触发器 : updating column depending of a submitted value

Question

这是我的触发器，但它不起作用。

CREATE TRIGGER events_events_a BEFORE INSERT ON events_events
FOR EACH ROW
BEGIN 
IF NEW.public = 1 THEN
UPDATE events_cats SET etotal=etotal+1, etotal_NEW.region=etotal_NEW.region+1 WHERE id=NEW.category;
END IF;
END;

我需要根据提交的值更新列。

if NEW.region value is 1, I need to update column etotal_1=etotal_1+1
if NEW.region value is 2, I need to update column etotal_2=etotal_2+1
if NEW.region value is 3, I need to update column etotal_3=etotal_3+1

等 有什么方法可以根据 NEW.region 值更新列吗？

Answer 1

您不能创建新的列名。对于 update 和其他 SQL 语句都是如此。您可以明确列出要更新的列:

UPDATE events_cats
    SET etotal = etotal + 1,
        etotal_1 = (case when new.region = 1 then etotal_1 + 1 else etotal_1 end),
        etotal_2 = (case when new.region = 2 then etotal_2 + 1 else etotal_1 end),
        etotal_3 = (case when new.region = 3 then etotal_3 + 1 else etotal_1 end)
    WHERE id = NEW.category;